Support of custom HTTP methods

[lfcipriani]

Support custom HTTP methods such as PURGE, or anything else

[rogerleite]

Actually only v2.2.0.rc1 version of httpi, supports custom method.

The net/http adapter only supports [:get, :post, :head, :put, :delete], i'll have to pull request this improvement.

[lsdr]

It sure would be nice to add support for OPTIONS and PATCH.