Add support for `force` configuration option

[bricestacey]

This is an option I find in version 2.2 to "Kill other running Browserstack Local".

Also had to bump jshint maxcomplexity.

[lucasfeliciano]

:+1:

Are you still using this module in a project? How it is working?

[pghalliday]

thanks, i'll release a new version shortly