XWIKI-9405: Add a "Wiki Creation" right.

* Rename "SubWikiCreation" right to "WikiCreation" right.
XWIKI-9405: Add a "Wiki Creation" right.

* Rename "WikiCreation" right to "CreateWiki" right.
Merge pull request #152 from gdelhumeau/XWIKI-9405

XWIKI-9405: Add a "Wiki Creation" right
* Rename "Subwiki" in "Wiki" and changed right name after suggestion from Eduard Moraru