AMEC-1979: make this class serializable.  This is necessary since rhino stores these in memcached, and the spymemcached library requires that stored objects be serializable.  This change should be completely irrelevant to ambra proper.
Add a no-op implementation of Cache, which will be used in rhino for dev mode, when memcached is not desired.
Merge branch 'master' into dev-AMEC-1979
Merge branch 'dev-AMEC-1979' into release/2.8.7rc
setting v in pom to 2.8.7
adding release notes