Fix IDEUI-220 Docker image creation as progress

Docker image creation was wrongly reported as if app was running. Now
it is reported as in progress.
Change the UndoableEditor to allow independent editor implementation to
satisfy the requirement
Have EditorWidget extends UndoableEditor
JsEditor implementation implements UndoManager
code clean up
Move ProjectTemplateDescriptionLoader form ide to api-project
IDE-288 Disable splitter when a part is hidden
Merge pull request #202 from codenvy/code_clean_up

code clean up
Merge pull request #201 from mleduque/IDEX-1154

IDEX-1154 undo/redo in jseditors
Merge pull request #199 from stephanedaviet/IDEUI-220

Fix IDEUI-220 Docker image creation as progress
Merge pull request #200 from kevinpollet/IDEUI-288

IDE-288 Disable splitter when a part is hidden