XWIKI-9415: Create a new SubWiki creation wizard.

* I have replaced WorkspaceManager.CreateNewWorkspace by my new wizard. I'm not sure about how this page should be called.
* In the future, I would like to make a new "createSubWiki" action in XWiki, and put this wizard in a .vm instead of having it on a page.
XWIKI-9415: Create a new SubWiki creation wizard.

* Fixing translation keys.
* Adding a check to see if a workspace template exists.
XWIKI-9415: Create a new SubWiki creation wizard.

* Replacing .wizard-half by .wizard-body .half
XWIKI-9415: Create a new SubWiki creation wizard.

* Rename "subwiki" to "wiki".
Merge pull request #149 from gdelhumeau/XWIKI-9415

XWIKI-9415: Create a new wiki creation wizard