Add DockerLogInput
Bugfix in CMakeLists
renamed dockerlog package and cmake options to docker
Updated cmake configuration

Cmake doesn't like dashes in tag names for some reason...
Updated documentation and CHANGES.txt
Better error handling and logging in DockerInputPlugin
DockerLogInput: use RWMutex instead of Mutex
Fixed typo
Merge remote-tracking branch 'upstream/dev' into dockerinput

Conflicts:
	CHANGES.txt
DockerLogInput: Use error instead of AttachError
Implemented ClientPinger
Wrap the go-dockerclient with an interface
Merge branch 'dockerinput' of github.com:carlanton/heka into carlanton_docker_input

Conflicts:
	CHANGES.txt
	build.bat
Switch to using go-dockerclient fork so we can get notified via channel
closure and exit the input plugin when the Docker daemon is stopped.
Merge pull request #1145 from mozilla-services/carlanton_docker_input

Carlanton docker input