[BUGFIX] #177 Frequent failures of remote git commands

[kyungmi]

This PR includes refactoring on all container implementations because it is hard to solve this problem without refactoring.

[IMPROVEMENT] Refactoring on containers and console-manager

• add new Container.js (old. exec.js) as a super class of all containers
• let container implementations(lxc, docker, lxcd, none) execute(commands or terminal) and kill by itself. (Remove dependencies on console-manager)
• fix some method names for understanding
  • change createFs and deleteFs of containers to create and destroy
  • change destroy method called after terminating current execution to onTerminated
• modify git.sh file to be also worked in host server

  [BUGFIX] Frequent failures of remote git commands

• make an exception for execution of git.sh to be excuted on the host because of its unstable action in LXC
• add new NOPASSWD commands in sudoers file

Related issue: #177