Add CLI version lower case -v alias - #1644

Most of CLI tools that are known to Modernizr
use lower case options. Let's mention only:
npm -v, node -v, bower -v, brew -v, git -v.
For some reason Modernizr CLI uses uppercase
-V option. This commit provides lower case alias
for now, so uppercase option can be phased out
in the future safely.

The tests:

>> 719 passed! (4.38s)
Done, without errors.

Before this change the well know -v was not supported:

modernizr -v
config file, inline features, or options required.

After this change the -v will work:

modernizr -v
Modernizr v3.0.0

The usage help will output:

modernizr -h
Options:
  -h, --help         Print Help                                                                                      
  -V, -v, --version  Print the version and exit 

Thanks!