Fix test failure
Remove some unused messages
Fix property key
Alias zanataMessages to messages; implement Map
Replace EL in messages.properties with positional parameters

Also switch ZanataMessages from Seam EL interpolation to
using java.text.MessageFormat.
Move zanataMessages alias into ZanataMessages.Factory
Rename ZanataMessages to Messages, component name "msgs"
Update javadoc for Messages
Merge pull request #517 from zanata/zanata-messages

Zanata messages