Create Exec agent

[skabashnyuk]

We need machine agent that is able to expose REST (or/and websocket) API for commands execution.

We considered that it should be written using Golang.

• it will allow deploy it without external dependencies such as JRE, NodeJs, etc
• it is fast and has small memory footprint
• it has very good model for processing http requests, websockets, execute commands in the OS
• it is quite easy to port it into different OSes and CPU architectures

[skabashnyuk]

@evoevodin

Current state:
I've developed a prototype of machine-agent which has RESTFul API for managing processes and
not full set of websocket API for managing processes through websocket channels.

The prototype repository: https://github.com/evoevodin/machine-agent
The docs for available REST API.
The docs for available Websocket API.
The docs for available Events(messages sent to the websocket channel clients).
Things TODO:

• The REST API, is not fully completed it needs a few more methods.
• Websocket API, is not fully completed right now it provides 2 methods for starting and killing proceses.
• Integrate terminal into machine-agent.
• Use configuration flags instead of hardcoded values(e.g. for logs directory)
• Not clear for now, when to clear resources(channels, processes, logs).
• Tests are not there at the moment.

[JamesDrummond]

NTS I will add these docs to the codenvy repo docs folder which will get moved to che repo once we are finished with creating codenvy docs jekyll generated doc pages.