Make search API of github library work again

[tkvogt]

Using recent patch to http-types to fix github issue #262.

[snoyberg]

I don't follow how the added function address the title in this PR. Also, can you include a change of entry and bump the version in the cabal file?

[tkvogt]

I forgot to mention this issue, where it is explained.
Github library uses http-client which uses http-types. http-types now allows to explicitly say which part of the query to encode. If you merge this patch, it is possible to use '+' or ':' in a search keyword, or what is more important to prevent '+' and ':' to be URL encoded and destroy a query like this:

?q=a%2Bcreated%3A2012-12-07..2012-12-17

[snoyberg]

OK, got it, this makes sense now. There's only one problem still: Stackage has been unable to upgrade to the newer version of http-types because so many packages are incompatible with it. I think it would make sense to make this new function's presence conditional on the version of http-types, instead of adding a lower bound.

[snoyberg]

This removes the lower bound, but doesn't make inclusion of the function conditional on the http-types version, meaning that this will simply break for older versions of http-types (Travis and AppVeyor will likely demonstrate this).

[snoyberg]

Thanks!