Please add semantic version tags

[gtmtg]

Although the README makes reference to CocoaPods, I couldn't find OPTableView, so I’ve recently added it by submitting this pull request.

However, OPTableView doesn't have any version tags. I’ve added the current HEAD as version 0.0.1, but a version tag will make dependency resolution much easier.

Semantic version tags (instead of plain commit hashes/revisions) allow for resolution of cross-dependencies.

In case you didn’t know this yet; you can tag the current HEAD as, for instance, version 1.0.0, like so:

$ git tag -a 1.0.0 -m "Tag release 1.0.0"
$ git push --tags

Also, please update or remove the podspec file in this repo, as it is outdated.