Readme reflects min macOS requirement of 10.11

Summary: Closes Instagram#1089

Differential Revision: D6918813

Pulled By: rnystrom

fbshipit-source-id: 13586a4ce3515538f6ef8f8ccebd58900d1fc306

Fix binding SC deselection crash and publish 3.1.1

Summary:
- Fixed Instagram#918 by checking `respondsToSelector:` (boo optionals)
- Cut 3.1.1 for immediate publish

- [x] All tests pass. Demo project builds and runs.
- [x] I added tests, an experiment, or detailed why my change isn't tested.
- [x] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
Closes Instagram#921

Differential Revision: D5748009

Pulled By: rnystrom

fbshipit-source-id: b387b3988abc785f312bc47ac003851283972d7a

Pod install 3.1.0

Summary:
Updating example pods via script
Closes Instagram#911

Differential Revision: D5695840

Pulled By: rnystrom

fbshipit-source-id: 7aaaf9f07e0aa0cccbebbcbd12d9e5a617755cf1

final docs update for 3.0

Summary: Closes Instagram#738

Differential Revision: D5052802

Pulled By: jessesquires

fbshipit-source-id: b1ace763da9edbb7bc65ecb9af34aa791e617aa7

Release 2.1.0 prep

Summary:
Prepping for `2.1.0`

- [x] Bump version numbers
- [x] Rebase this branch after remaining PRs are closed
- [ ] Run `pod install` (**must be done internally**)
- [x] Re-gen docs
Closes Instagram#380

Reviewed By: rnystrom

Differential Revision: D4381222

Pulled By: jessesquires

fbshipit-source-id: 04646168d3c84d0dd2c08f0a357836b9326f8963

Update CHANGELOG.md

Summary: Closes Instagram#311

Differential Revision: D4307618

Pulled By: jessesquires

fbshipit-source-id: 0698436fdeeec9c6d4a776376572025e6e8e6ee4

Pod file updates

Summary: Pod files were skipped after API renames.

Reviewed By: jessesquires

Differential Revision: D4003106

fbshipit-source-id: d3b5336a8e98880549d4414d679cbeff94169a01