pull request for IEC 62056-21 binding

forked again from openhab and added new binding for for IEC 62056-21
meter binding
added configuration IEC 620562-21 Meter Binding
improve update of number items

improve update of number items
remove file
Update openhab_default.cfg
merged with current master
rollback to master version
implemented review comments fom pull request 1040
remove class, will be moved to seperate test project
refactored meterdevice and cleaned up classes
Merge branch 'IEC-620562-21-Meter-Binding' of https://github.com/kreutpet/openhab into kreutpet-IEC-620562-21-Meter-Binding #1040
fixed usage of deprecated maven variable
added iec6205621 to distribution build