Added an XPC service to deal with sandboxing.

This fixes #163. It requires that you copy the XPC service into your main application bundle in
Contents/XPCServices and runs the remove from quarantine step of copying the finish_installation
app as well as launching finish_installation app outside of the sandbox. Sparkle will function
exactly as it does now for applications that do not copy the XPC service into their application
bundle.
Add explicit method return types in header to supress warnings when including framework in projects with more exacting warnings such as -Wextra.
update .gitignore
Fix "corrupted" turkish strings file
Update Project file/Scheme to recommended Xcode settings
Fix stuffing unsigned int into int variable, causing build warning
Merge remote-tracking branch 'wbyoung/master'

Conflicts:
	Sparkle.xcodeproj/project.pbxproj
	finish_installation.m
Merge pull request #240 from ryanmaxwell/master

Correct build warnings for 3 issues - detailed in each commit
Merge pull request #229 from mugginsoft/master

Hush method return type warnings when importing SUUpdater.h
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Fixing issue with update as non admin user where the quarantine flag did not get correctly removed from new application
Merge branch 'master' of https://github.com/andymatuschak/Sparkle