Fixed issue #34

Clue of this commit is here: http://stackoverflow.com/questions/24099520/commonhmac-in-swift
Merge pull request #35 from gecko655/SHA1DigestWithKey

Fixed crash when generating SHA1 digests, fixes #34
Change + to +| for Dictionary

Fixes issue where + operator was breaking for normal math in file that
the framework was imported into.
Support Swift language changes in Xcode 6.1

(Note these changes will not work with Xcode 6.0)

- Added UnicodeScalarLiteralConvertible protocol to JSON
- Added explicit unwrapping where needed e.g. optional NSURL (ideally
we should check for errors first before using the returned objects),
UITableViewCell constructor is now also optional
Merge pull request #37 from joalbright/master

Change + to +| for Dictionary+Swifter.swift
Merge pull request #38 from heidiproske/master

Support Swift language changes in Xcode 6.1