Mirgrating feature_rest_api changes into h2o-steam:

Squashed commit of the following:

commit a25a6cf900a6331b919c57c9935abefe71346f6f
Author: mmalohlava <michal@0xdata.com>
Date:   Thu May 15 14:04:04 2014 -0700

    Missing file.

commit 6e7fca03115d78e65770c909fa9f2fb5e2c26309
Author: mmalohlava <michal@0xdata.com>
Date:   Thu May 15 13:55:44 2014 -0700

    Weaver stuff

commit 2d869e936d0d8328b34d270660c4cedd62dd8ddc
Author: mmalohlava <michal@0xdata.com>
Date:   Wed May 14 17:06:23 2014 -0700

    Added basic transformers for
    String and Frame, Key, Vec

commit 845088ae6d24bcdd8c7dc092d5246c34546b07ee
Author: mmalohlava <michal@0xdata.com>
Date:   Wed May 14 12:54:21 2014 -0700

    WIP: declarative adaptor

commit 8ca8eed4099dce33b82cad79321428b1f571ebc1
Author: mmalohlava <michal@0xdata.com>
Date:   Mon May 12 17:30:16 2014 -0700

    WIP: refactoring

commit 72caafd7fe850ecccb412152c5d48fc560269437
Author: mmalohlava <michal@0xdata.com>
Date:   Mon May 12 15:39:56 2014 -0700

    More experiments.

commit 993f20d791bba05e866e19fb9424d1ba76940c4a
Author: mmalohlava <michal@0xdata.com>
Date:   Mon May 12 15:20:49 2014 -0700

    Bloody adaptor for bleeding edge rest api.

commit bf4f043be7ae4fe561888bf2e428a1aee2ab1da8
Author: mmalohlava <michal@0xdata.com>
Date:   Mon May 12 14:01:02 2014 -0700

    Adaptor for GBM, extended annotation.

commit 85674c6edac03fa39ad0d1305147a82a7c9785e6
Author: mmalohlava <michal@0xdata.com>
Date:   Fri May 9 16:43:27 2014 -0700

    WIP: dummy prototype of adaptor from REST and Impl