List tags of videos retrieved with Video#search

YouTube API only returns tags on Videos#list.
To show the tags even for videos instantiated through Video#search
(e.g., by calling account.videos or channel.videos), the partial
snippet is reloaded to obtain the full snippet (with tags),
rather than the partial one.
Merge pull request #68 from Fullscreen/fix-tags-on-video-search

List tags of videos retrieved with Video#search
Add support for PATCH requests

Currently only YouTube Partners API supports PATCH, while YouTube
Data API still only has support for PUT requests to update resources.

The Patch action is introduced and used in the only Partner resource
that can get updated by Yt so far: MatchPolicy.
Merge pull request #69 from Fullscreen/add-patch-support

Add support for PATCH requests
Bump version to 0.10.5
Add `log_level` to Yt.configuration

Rather than always printing out a verbose error message in case of
failure, Yt now supports log levels which can be set through
`Yt.configuration.log_level`:

- `:devel` is the most verbose, printing the curl format of every request before it’s run
- `:debug` matches the previously existing behavior, showing response body and request curl of failing requests
- any other value (or nil) is the least verbose, hiding response body and request that caused a YouTube error
Revert "Remove encrypted keys from .travis.yml"

This reverts commit 797ceecd40f6252d83b170ee9c84b16026a29fc4.

With the new `log_level` configuration, it is now secure to
restore Travis CI.
Merge pull request #73 from Fullscreen/add-log-level

Add log level
Add Video search without a parent account/channel

For instance, search for the most viewed video on the whole YouTube running:

```ruby
videos = Yt::Collections::Videos.new
videos.where(order: 'viewCount').first.title #=>  "PSY - GANGNAM STYLE"
```
Merge pull request #72 from Fullscreen/yt-video-where

Add Video search without a parent account/channel
Add Yt::Collection::Videos to README
Make CHANGELOG format compatible with Gemnasium

The log shown at https://gemnasium.com/gems/yt/versions does not
support markdown code ```, so just indent it instead.

[ci skip]
Merge branch 'update-changelog-for-gemnasium'
Bump coveralls and rspec
Merge branch 'bump-gems'
Remove Gemfile.lock from gem

Gems should not have Gemfile.lock in version control, see
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/

[ci skip]
Ignore Gemfile.lock in git

Gems should not have Gemfile.lock in version control, see
http://yehudakatz.com/2010/12/16/clarifying-the-roles-of-the-gemspec-and-gemfile/

[ci skip]
Remove duplicate method `underscore_keys!`
Merge branch 'remove-duplicate-code'
Remove duplicate method `underscore_keys!`

One duplication was left after 148d470b