Fix insecure format string warning.
Remove ancient, irrelevant build settings.
Allow SDK and compiler to be set by Xcode automatically.
Remove unnecessary double quotes from Xcode build settings.

Xcode will already quote these as necessary.
Merge pull request #467 from petroules/appledoc-fixes

Appledoc fixes
Update GRMustache to v7.0.3
Merge pull request #469 from sptramer/grmustache-update

Update GRMustache to v7.0.3
Fixed crash due to arguments count assertion. Closes #470 and #472.
Added link to wiki pages. Closes #476.