Re-enable Resource Content API

On 0.2.9 release, we temporarily disable resource content service due to:

• First, it was very slow on repositories with multiple files on Github, making the editor slowdown;
• It was not working on Github 'edit' mode
• Icons are not working on windows (probably related with path)
• There's an exception happening when the editors open. See BPMNSessionInitializer line 66.

Until we fix this, we will not have work item definitions integrated on our tooling. So this blocks that feature.