Add initWithName:rootPath:

Used to store the cache in a different directory than the NSCachesDirectory (an offline data folder for example).
Fix pull request merge conflict
Importing Foundation, so TMCache can be used in Swift projects
Recursively compute disk cache sizes
Fix error logging calls
Merge pull request #53 from vmartinelli/master

Importing Foundation, so TMCache can be used in Swift projects
Use NSURLTotalFileSizeKey
Merge pull request #54 from segiddins/recursive-size

Recursively compute disk cache sizes
Revert "Recursively compute disk cache sizes"
Merge pull request #55 from tumblr/revert-54-recursive-size

Revert "Recursively compute disk cache sizes"