Add an prompt to install the required dependencies after generating coafile

[satwikkansal]

This could be another step in increasing automation. We can generate a shell script file that has commands to install the dependencies of all the bears in the written ".coafile" which are not already installed on user's system. The user can then modify (if he wants) and run the script to install the dependencies.

Not sure if coala does this already?

status/needs design

[jayvdb]

The user would do this by installing and using https://gitlab.com/coala/cib , which is broken atm and is another one of the projects this year.

[jayvdb]

Overlaps a lot with https://github.com/coala/coala-quickstart/issues/33