Fix issue #34

- Implemented CookieStore class which has an ability to serialize and
deserialize its CookieContainer.
- Synced IHttpClientFactory interface with the Android’s implementation
: including cookie related method and making changes to all the classes
that implement the interface.
- Modified DefaultAuthHandler to pass CookieStore as one of its
constructor. DefaultAuthHandler will call the Commit() method on the
CookieStore object to persist the CookieContainer when it detects
‘Set-Cookie’ in the response header.
- Added CookieStoreTest for testing the CookieStore class.
- Added TestSetAndDeleteCookies() in ReplicationTest.
Any particular reason this isn't a read-only property?