[iOS] Add If-Match and Precondition handling to DeleteWithItem
Fix #164: allow creation of MobileServiceClient with no app key.
Merge pull request #250 from carlosfigueira/Github164

[android] Fix #164: allow creation of MobileServiceClient with no app key.
[client][js] support for optimistic concurrency on delete
Merge pull request #251 from hasankhan/jsocdelete

[client][js] support for optimistic concurrency on delete
Merge pull request #252 from phvannor/dev

Use VS2013 auto nuget restore
Merge branch 'dev' into deleteWithOC
Add test for empty JSON object in body
Merge pull request #239 from toddreifsteck/deleteWithOC

[iOS] Add If-Match and Precondition handling to DeleteWithItem