Fixed bugs in project Settings.
Made ContentProvider Thread-save.
Implemented Batch Mode in Content Provider. Not tested.
-Added Columns "isVirtual" and "uniqueId" to itemsDetails table in Content Provider.
Minor Changes in Settings Fragment. Renamed a few variables.
Added Column projectId to Table itemsDetailsRO in Content Provider.
-Finished add_new_item Activity.
-Fixed a fast amount of bugs.
-Linked itemlist Activity
-Made items deletable.
-implemented total expenses calculation.
-Fixed bug in ContentProvider
-Created participantsList Fragment
Merge branch 'itemListFragmen_and_addItemActivity' into guis_for_chrissy

Conflicts:
	app/src/main/res/values/strings.xml