Add license field to gemspecs

[betamatt]

Added license = "MIT" to all gemspecs.

Life would be simpler if all gems declared their license but currently few do. This is important information when declaring the licenses an application is dependent upon in due-diligence scenarios (such as startup funding.)

[grosser]

can the gems still be installed on old rubygems versions <-> will there e an undefined method licence= error ?

[betamatt]

That's a great question. How old is necessary? I've verified that it's supported at least as far back as 1.3.6 but if you're concerned about ancient versions I can try to see how far back it can go.

[betamatt]

Appears to install fine.

Created a gem with a license in the specification on rubygems 1.5.3.
Installed cleanly on rubygems 1.0.0. Was able to load the gem from irb.

[arunagw]

@betamatt Your PR needs a rebase

[betamatt]

@arunagw Rebased.

[arunagw]

cc/ @josevalim

[rafaelfranca]

This pull request cannot be automatically merged. If you want to apply this one, please rebase it against the master. I'll be glad to ask someone from the Core Team to review it. If you don't want, please close it.

Thanks.

[grosser]

the speed of progress is just breathtaking.... such a major change, just fetch and pick it :D

[arunagw]

Rebase Rebase and Rebase... Let's Rebase again :-)

[arunagw]

Closing this as @grosser cheery-picked the same and did a PR #6462