fix(dateFilter): make timezone optional

Makes the time zone optional in the date filter

Problem with the current R_ISO8601_STR regex was that the time was optional, but the zone was not.
This results in the filter not formatting local date times, which it could easily do.

For example:
2012-08-30 -> formatted
2012-08-30T06:06:06.123Z -> formatted
2012-08-30T06:06:06.123 -> NOT formatted

A simple change in the regex fixes this. Arguably this is closer to the ISO8601 spec which specifies
local dates being in the "current time zone" and not requiring a Z. In any case it behaves more like
a user would expect.

src/ng/filter/filters.js

@@ -320,7 +320,7 @@ dateFilter.$inject = ['$locale'];
 function dateFilter($locale) {
 
 
-  var R_ISO8601_STR = /^(\d{4})-?(\d\d)-?(\d\d)(?:T(\d\d)(?::?(\d\d)(?::?(\d\d)(?:\.(\d+))?)?)?(Z|([+-])(\d\d):?(\d\d)))?$/;
+  var R_ISO8601_STR = /^(\d{4})-?(\d\d)-?(\d\d)(?:T(\d\d)(?::?(\d\d)(?::?(\d\d)(?:\.(\d+))?)?)?(Z|([+-])(\d\d):?(\d\d))?)?$/;
   function jsonStringToDate(string){
     var match;
     if (match = string.match(R_ISO8601_STR)) {

test/ng/filter/filtersSpec.js

@@ -258,6 +258,9 @@ describe('filters', function() {
 
       expect(date('20030910T033203-0930', format)).toEqual('2003-09 03');
 
+      //no timezone
+      expect(date('2003-09-10T13:02:03.000', format)).toEqual('2003-09 03');
+
       //no millis
       expect(date('2003-09-10T13:02:03Z', format)).toEqual('2003-09 03');