Create LICENSE

Added License file.
Updated Readme to include section about License

I Updated the README to include a section about License, we are using, which is BSD. Which is the same as the Master Sentry project.
Add missing info to pom to release to maven central.
Merge pull request #34 from alfakini/master

Add missing information to POM.
updated pom.xml to include email address

updated pom.xml to include ken cochrane's email address
Merge branch 'refactoring' into master
Merge branch 'refactoring' to include raven-logback
Remove "encoder" property from logback.SentryAppender
Update README
Add a parameter checksumContent to generate a custom checksum

Default on the message if the checksumContent isn't provided
Use a checksumContent in order to group exceptions and messages

Exceptions are now grouped by stacktrace content which should be more
relevant than exception messages
Simple logs are grouped by locationInformation (line where the log was done)
if available, message otherwise.