Allow for mac development

Some of the code was tied to UIKit, make it only included when doing
iOS development.
Actually allow for mac development

finally actually works.
Merge pull request #82 from elgreco84/master

Removed the NSAssert which was breaking the delete code and should never...
Properly implements NSCopying. Adds fetchCurrentUser
Merge pull request #83 from derrh/master

Properly implements NSCopying. Adds fetchCurrentUser
update podspec v0.42
Merge pull request #84 from derrh/master

v0.42
Merge remote-tracking branch 'instructure/CanvasKit/master'

Conflicts:
	CanvasKit.podspec
	CanvasKit/Networking/CKIClient.m
get rid of some warnings
Merge pull request #81 from jarsen/master

Allow for Mac Dev
add submission fetching
add CKISubmissionSet
add networking for CKISubmisionSet
add userID to CKISubmissionSet
make userID property on CKISubmissionSet actually work

use the provided setter, duh.
update podspec to 0.44
Merge pull request #85 from jarsen/master

Submissions