Merge pull request #1 from sksamuel/master

Sync with master
Don't use empty plugin switches

Scala 2.11.4 breaks when passed plugins that are empty.  `disabledInspections`, `enabledInspections`, and `ignoredFiles` are all empty by default so this excludes them unless they are provided.
Merge pull request #13 from lespea/master

Don't use empty plugin switches