Add g:EclimJavaImplAtCursor setting + implementation

This will resolve my issue #356

Also fixes a bug where the length of the inserted code was not
quite accurately calculated, causing the method next to
that inserted (the sibling) to have its indentation messed up
Fix checkstyle warnings
Merge remote-tracking branch 'dhleong/dhleong/EclimJavaImplAtCursor' into impl-insert-location
rename g:EclimJavaImplAtCursor to g:EclimJavaImplInsertAtCursor

update the name to better convey what it does without reading the
setting docs.