BinDeps keyword argument validation

[staticfloat]

Tested on OSX.

[nalimilan]

Thanks for this! Though looks like you need to support os (or at least accept it with a deprecation warning).

[staticfloat]

Yep, missed a bunch because I was only looking for get(opts, :arg) instead of haskey(opts, :arg).

[tkelman]

Bump. I forget, was this ready to go?

[staticfloat]

We should run the tests again just in case.

[staticfloat]

There, I just rebased onto master. Let's make sure everything is still green.

[tkelman]

Apparently HttpParser hasn't been fixed since we removed the 0.4 deprecations on nightly. HttpParser has some API changes not yet resolved that mean it currently can't be tagged until an upgrade path is put in place for existing installs... and windows binaries are rebuilt for the new version. Will need a more precise validation callback etc but this is an issue for a different repo...