new mapped tags to appender
new mapped tags parameter test
updated README with new mappedTags option
removed redundant imports
removed debug print from appender
Fixed code style issues
Merge branch 'master' into test
Merge branch 'master' into mdc-tag

Conflicts:
	raven-log4j/src/main/java/net/kencochrane/raven/log4j/SentryAppender.java
Merge branch 'master' into mdc-tag
Ensure that extra tags aren't sent as extras as well

Use a Set rather than a list for the Extra tags
Add documentation and improve test coverage
Add extra tags to log4j2
Add extra tags to logback
Add upport of MDC and extra tags to JUL (with SLF4J support of MDC)
Merge branch 'master' into mdc-tag

Conflicts:
	raven-log4j/src/main/java/net/kencochrane/raven/log4j/SentryAppender.java
	raven-log4j2/src/main/java/net/kencochrane/raven/log4j2/SentryAppender.java
	raven-logback/src/main/java/net/kencochrane/raven/logback/SentryAppender.java
Fix api calls
Update documentation