Update issue templates

I've created 3 types of templates based on those in the wiki and the default (bug) issue template. These can be edited or additional ones added at your leisure.

I also added the OFN software instance and version to the bugs template

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,61 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+## Description
+<!-- Provide a more detailed introduction to the issue itself, and why you consider it to be a bug -->
+
+
+## Expected Behavior
+<!-- Tell us what should happen -->
+
+
+## Actual Behaviour
+<!-- Tell us what happens instead -->
+
+
+## Steps to Reproduce
+<!-- Provide an unambiguous set of steps to reproduce this bug -->
+<!-- Include code to reproduce if relevant -->
+
+1.
+2.
+3.
+4.
+
+## Animated Gif/Screenshot
+<!-- Provide a screenshot or brief animated gif reproducing the bug. Linux users can use
+[Peek](https://github.com/phw/peek#ubuntu) while Mac users can use [Recordit](http://recordit.co/) -->
+
+
+## Context
+<!-- How has this bug affected you? What were you trying to accomplish? -->
+
+
+## Severity
+<!-- Assign a label and explain the impact.
+
+bug-s1: a critical feature is broken: checkout, payments, signup, login
+bug-s2: a non-critical feature is broken, no workaround
+bug-s3: a feature is broken but there is a workaround
+bug-s4: it's annoying, but you can use it
+bug-s5: we can live with it, only a few users impacted
+
+https://github.com/openfoodfoundation/openfoodnetwork/wiki/Bug-severity
+-->
+
+## Your Environment
+<!-- Include relevant details about the environment you experienced the bug in -->
+
+* Version used:
+* Browser name and version:
+* Operating System and version (desktop or mobile):
+* OFN Platform instance where you discovered the bug, and which version of the software they are using. 
+
+## Possible Fix
+<!-- Not obligatory, but suggest a fix or reason for the bug -->

.github/ISSUE_TEMPLATE/feature-template.md

@@ -0,0 +1,35 @@
+---
+name: Feature template
+about: Create feature epics that detail the larger feature or functionality to be
+  delivered.
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+## What is the problem we are solving 
+<!-- Describe the problem this feature is supposed to solve. Should be described in the icebox item (in Discourse). -->
+
+## Success factors = expected outcome 
+<!-- Describe what is the expected outcome: when the feature is released, what would it look like? What will make you say "the problem is solved"? Can be metrics like "Platform has less than 1% service interruption", or yes/no statements like "People can checkout on mobiles. -->
+
+## Useful information for inception
+<!-- List here any information that can be useful for the inception stage. -->
+
+## Link to the "Product Development - Backlog" item in Discourse
+<!-- Put the link here, and put this epic link in the Discourse item as well for cross-referencing. -->
+ Add a custom footer
+ Pages 70
+Home
+Development environment setup
+
+macOS (Sierra, HighSierra and Mojave)
+OS X (El Capitan)
+OS X (Mavericks)
+Ubuntu
+On Heroku
+Rubocop
+General guidelines
+
+Spree Commerce customisation

.github/ISSUE_TEMPLATE/story-template.md

@@ -0,0 +1,18 @@
+---
+name: Story template
+about: Create stories that are small chunks of work that devs will pick up and deliver
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**## Description**
+<!-- Describe the story in detail:
+**- As a:** (enterprise user, super admin, user...)
+**- On page:** (provide url of the page you want to modify. If not provide where will be created the new url and the name we want to give it)
+**- I want to be able to do:** (specify the desired behavior)
+(Link to others issues or resources to provide context > only if really necessary). -->
+
+**## Acceptance Criteria**
+<!-- Document the outcomes that need to be achieved before this component can be considered complete. -->