initial implementation of JPA persistence binding.
added jpa config values in openhab_default.cfg
fixes to transaction management in jpa persistence service. a new entitymanager is created and closed for each transaction.
only name refactorings.
some modification for a separate configuration class (as in db4o binding. This modularity will help in unit tests.
some refactorings. considering varchar uses 4 byte if empty made me switch to a one entity approach having a simgle value column which can take upto 200k.
minor simplifications.
Merge branch 'master' of https://github.com/mdbergmann/openhab
added first test.
reduced size of value column to 32k which is the max size for derby.
Merge branch 'master' of https://github.com/openhab/openhab
minor adjustments for Derby database in column size.
removed first test sqljpa binding reference in binding/pom.xml
reverted unintended changes to other parts of openhab.
Merge pull request #1210 from mdbergmann/master

initial checkin of the JPA Persistence Binding