Adding readme, UPGRADE notes
Fix grammar
Typo
Removing 1.5 -> 2.0 upgrade notes
Merge pull request #612 from khawkins/doc_updates

Readme, upgrade notes
Merge remote-tracking branch 'upstream/unstable' into unstable23_merge
Merge pull request #613 from khawkins/unstable23_merge

Mobile SDK: Merging unstable to unstable23