Added a unit test verifying revpos changes when attachment is updated.
Updating LICENSE.txt to 2011-12-07 CE License

This is per requirement
CBLT-229: added: LICENSE_enterprise.txt, renamed: LICENSE.txt -> LICENSE_community.txt

Parent must copy appropriate file to LICENSE.txt before calling.

Change-Id: I5028e53392a927d2848c7e04995164eeb3bc5e3c
API Change: Added CBLAuthenticator

Pre-existing CBLReplication auth methods are still present,
but the ones supported by CBLAuthenticator are deprecated.
REST API replication auth works as before.
Added some missing copyright/license comments.
Catch uncaught exceptions in CBLDatabase doAsync etc.

Otherwise GCD tends to kill the process, which means unit testing can’t complete.
Fixes #309
Bumped version number to 1.5 for GA
Comply with EE change for 2014-04-14

This is for packaging only.
CBLT-268:  product version now set to a token, instantiated at build time:

    CURRENT_PROJECT_VERSION = @PRODUCT_VERSION@;
    CURRENT_PROJECT_COMMIT  = @COMMIT_SHA@;

Change-Id: I43bbfeb3452fa25301d1416db87745469e678f8f
Revert "CBLT-268:  product version now set to a token, instantiated at build time:"

This reverts commit ee5212dd5c79c0e40587a55659478d5eb621d01d.
Merge branch 'master' of https://github.com/couchbase/couchbase-lite-ios