IDEX-1323

After merging this pull request need to merge the following:
- https://github.com/codenvy/plugin-datasource/pull/219;
- https://github.com/codenvy/plugin-git/pull/34;
- https://github.com/codenvy/plugin-hosted/pull/64;
- https://github.com/codenvy/plugin-java/pull/32;
- https://github.com/codenvy/plugin-sdk/pull/6.