Feature:Auto pull,build,restart application like Travis CI.

[zxl777]

When I push the new source code to Github.

APM should auto pull the github source code ,

if build done , auto restart the new application.

[MateusDantas]

That's a very nice feature. We do have a couple of tasks that are more high priority right now, but I will put this one up in the queue so I can do it later. If you have any suggestions or if you have a PR in mind, feel free to submit it and I will take a look.

My suggestion for this one is:

• [ ] Refactor ProcPreparable and move the building phase into a new module
• [ ] Create pull module
• [ ] Add auto-pull flag to APM

As we will start building projects outside the master, I think it's a wise move to make the building process a separate module. We will also need another module which will keep track of a process by constantly checking if there's a new version of it available. Then we let the build module handle it, and once it's done we signal to the master that we need to restart this process.

Things to be careful with:

• How are we gonna handle private repositories? If credentials are needed, are we gonna pass them over to the pull module?
• How do we handle the situation when the user doesn't want to have the auto pull option enabled anymore? We need to inform the auto-pull module to cease its operations in that particular process. We have to find a smart way to do this to avoid interaction with other processes.