Make a more generic solution: KeyValueMapStore

- As QueryPersistence, stored in the localStorage too but it is now more generic and has nothing to do with Query
 - Add some js unit testing

spec/javascripts/unit/admin/services/key_value_map_store_spec.js.coffee

@@ -0,0 +1,38 @@
+describe "Test KeyValueMapStore service", ->
+
+  KeyValueMapStore = null
+  
+  beforeEach ->
+    module "ofn.admin"
+
+  beforeEach inject (_KeyValueMapStore_) ->
+    KeyValueMapStore = _KeyValueMapStore_
+
+  it "set and restore filters", ->
+    KeyValueMapStore.localStorageKey = 'localStorageKey'
+    KeyValueMapStore.storableKeys = ["a", "b", "c"]
+    source =
+      a: "1",
+      b: "2",
+      d: "4"
+    KeyValueMapStore.setStoredValues(source)
+    source = {}
+    restored = KeyValueMapStore.restoreValues(source)
+    expect(restored).toEqual true
+    expect(source).toEqual {a: '1', b: '2'}
+
+  it "clear filters", ->
+    KeyValueMapStore.storageKey = 'localStorageKey'
+    KeyValueMapStore.storableFilters = ["a", "b", "c"]
+    source =
+      a: "1",
+      b: "2",
+      d: "4"
+    KeyValueMapStore.setStoredValues(source)
+    KeyValueMapStore.clearKeyValueMap()
+    source = {}
+    restored = KeyValueMapStore.restoreValues(source)
+    expect(restored).toEqual false
+    expect(source).toEqual {}
+
+