Fix BugZilla bug id 281
Merge pull request #47 from Larry0ua/master

Fix BugZilla bug id 281. Looks reasonable, all the isTraceEnabled line up with the trace() calls.
Add readme and enable travis-ci
Don't truncate logger names when API_LEVEL >=7

The limitation of 23 characters doesn't apply on SDK >= 7.
File-based log level configuration

Loggable levels are no more checked using Log.isLoggable(level) but using
a configuration file named "slf4j.properties" and located in "assets"
folder.
Unit test Logger configuration retrieved through LoggerFactory