Add: allow specifying module parameter on the command line

This patch allows users to specify the module parameter directly on the command line. For example, the command

    tsar --nginx:8899 --swift:9999 -i1 -l

will print live data collected from nginx and swift running on ports 8899 and 9999 respectively.

A colon (`:`) is used to separate the module name and the parameter. If `:` is found on the command line, tsar will start the module with the provided parameter. Otherwise the parameter given in the configuration file will be used.

In the daily development environments, it's a common case that multiple developers start the same server program on the same machine, but different ports. So it would be more flexible to specify the module parameters on the command line, since
* the developers do not need to edit the configuration file back and forth, and 
* they can use tsar to monitor the same program simultaneously