Make AngularJS-eclipse 'convert project ...' action bevare of that Tern.java
is able to treat a custom project nature as Tern nature.

Signed-off-by: vrubezhny <vrubezhny@exadel.com>
Merge pull request #50 from vrubezhny/makeTernAdaptableToOtherNatures

Make AngularJS-eclipse 'convert project ...' action bevare of that Tern....