Implement basis for osx version using psutil library

This is the start for implementing the OSX agent/client. It turns out that fetching cpu time and memory usage for a process through python on OSX is not trivial. One option would be to parse **ps** return. But this is slow. Instead I found a portable python package that does the job for us. It is called [psutil](http://pythonhosted.org/psutil/). The cool part of using this library is that we can delegate platform support management. This would simplify our codebase. I propose we use psutil on all platform.

Another point to note, on OSX it is not possible (as far as I know) to get the exit code for a process unless you catch it while terminating. So I did not implement ProcessMonitor.exit_code() method you have on Windows. I did not understand its purpose too :(. Was it only for testing purpose?

**Bonus**: Integrated _pylintrc_ configuration file so we can push default parameters locally and on Travis
I understand. It is a one instance problem though :)

Here are the lines I changed from the default generated file:

_This chunk_
    
    # Add files or directories to the blacklist. They should be base names, not
    # paths.
    ignore=CVS

_is_now_

     # Add files or directories to the blacklist. They should be base names, not
    # paths.
    ignore=tests
  
_This chunk_

    # Disable the message, report, category or checker with the given id(s). You
    # can either give multiple identifiers separated by comma (,) or put this
    # option multiple times (only on the command line, not in the configuration
    # file where it should appear only once).You can also use "--disable=all" to
    # disable everything first and then reenable specific checks. For example, if
    # you want to run only the similarities checker, you can use "--disable=all
    # --enable=similarities". If you want to run only the classes checker, but have
    # no Warning level messages displayed, use"--disable=all --enable=classes
    # --disable=W"
    #disable=

_is now_

    # Disable the message, report, category or checker with the given id(s). You
    # can either give multiple identifiers separated by comma (,) or put this
    # option multiple times (only on the command line, not in the configuration
    # file where it should appear only once).You can also use "--disable=all" to
    # disable everything first and then reenable specific checks. For example, if
    # you want to run only the similarities checker, you can use "--disable=all
    # --enable=similarities". If you want to run only the classes checker, but have
    # no Warning level messages displayed, use"--disable=all --enable=classes
    # --disable=W"
    disable=similarities,fixme