Add checks to avoid NPE if not configuration defined for a device.
Merge pull request #22 from openhab/master

Merge with master
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
Initial copy, read-only at the moment, with support for Commands (limited)
Fix parameter labelling.
Handle conversion of Strings -> PercentType better so that inbound values for "Sliders" (aka Dimmers) come through correctly, and can be displayed in the UI.
Add example Command Mappings for the Lock command (DoorLock1) and for the Armed command (SecuritySensor1/SetArmed(...))
Move missing Command Transformation from a DEBUG to WARN level logging.
Add rudimentary parameter substitution model for Commands received by Devices.
For now, INCREASE/DECREASE actions received (legacy UI) are hard-coded but you can use a new syntax to express that you want the Command value itself substituted and the Device will pass it through to MiOS (see miosDimmerCommand.map, which needs to be attached to a Dimmer's binding via

    ...,command:MAP(miosDimmerCommand.map)
Add rudimentary documentation for the "command:" parameter, and how to use it to map command values.