Update pom.xml to 1.0.4-SNAPSHOT in preparation of more work.
Get rid of unnecessary comment.
Extract common logic of executing RefreshViolationsWorker.
Made cache generic.

Less code duplication between violation and source cache.
Fix NPE if looking at a file that isn't in Sonar.
Add original source code to inspection message.

In case line numbers have changed, the original source
  may help figure out the context of the violation.
Merge branch 'master' of github.com:gshakhn/sonar-intellij-plugin