Updated the BOOLFromNSString

In case a string is returned, it is also very likely to include YES, Yes, yes, true, True or True as possible values.
Check string for nil value

make sure to check the string for nil value before doing the caseInsensitiveCompare, otherwise this could introduce a bug.
- Using NSClassFromString instead of [JSONModel class], as this was breaking unit tests, see below

-
http://stackoverflow.com/questions/21394919/xcode-5-unit-test-seeing-wro
ng-class
Fix: force date parser to use military hours

This fixes an issue that occurs when device is set to use am/pm hour format and trying to parse iso 8601 datetimes, on which cases it retrieves nil.
Also dateFormatter is stored in static reference to avoid multiple allocations when parsing, improving performance.
Add a default JSONValueTransformer for NSNumber <-> NSDate

Uses the NSNumber as a timestamp since 1970.
Merge pull request #210 from vibrazy/unitTestFix

- Using NSClassFromString instead of [JSONModel class], as this was brea...
Merge pull request #227 from dbachrach/master

Add a default JSONValueTransformer for NSNumber <-> NSDate
Merge pull request #226 from restorando/master

Fix: force date parser to use military hours
static date formatter for speed optimization
Merge branch 'master' of https://github.com/icanzilb/JSONModel

Conflicts:
	JSONModel/JSONModelTransformations/JSONValueTransformer.m
Merge pull request #209 from NSMutableString/patch-1

Updated the BOOLFromNSString
little clean up
https://github.com/icanzilb/JSONModel/pull/208
https://github.com/icanzilb/JSONModel/issues/222
https://github.com/icanzilb/JSONModel/issues/217
https://github.com/icanzilb/JSONModel/issues/180
deprecate the core data functions, won't develop the lib in that direction
clean up
* 1.0.0 update
* removing CoreData dependency