Removed an unecessary parameter to MenuItem.create. Added the creator parameter for Page and Post create functions. Added the Page.createBasePage helper method. Corrected a NullPointerException in Site.fromSlug and added a missing nullification in Site.delete.
Post attachments are uploadable and sortable
Merge branch 'develop' of github.com:ist-dsi/bennu-cms into develop

Conflicts:
	src/main/java/org/fenixedu/bennu/cms/domain/Post.java
ignoring files generated by intelliJ
slug creation does not create a menu funcionality automatically
Posts pagination
Added modification date to Page and Post.
Added modification date to Page and Post. Corrected NullPointerException in Site.fromSlug.
Added a backend to allow sites to be embedded in a portal environment

  * Added proper access group for site's functionalities