Added development requirements
Added test for clean environment.
fix status function arguments
Don't show `-None-None` on the version.
Renamed sysmod module to docs module

This module is going to collect docs functions for all the module types
instead of just shadowing the execution sysmod module.
Added runner module docs; renamed module in virtual function
Added method to Wheel client to grab inline docs
Added function to grab wheel module docs
New states and modules for managing node.js packages with NPM
Merge pull request #3958 from s0undt3ch/hotfix/version-guild-git-tag-fix

Don't show `-None-None` on the version.
Merge pull request #3910 from rca/make_copy_of_environment

Test making copy of environment
Merge pull request #3961 from chideit/npm

New states and modules for managing node.js packages with NPM
Merge pull request #3959 from whiteinge/salt-runner-doc

Change the sysmod runner to a more general docs runner
Merge pull request #3960 from seanchannel/develop

basic output / message fixups
Merge pull request #3955 from giantlock/develop

fix status function arguments
Be more helpful when missing arguments.

BEFORE:
```
(code-salt)salt:~/code/salt # salt salt test.echo
salt:
    Traceback (most recent call last):
      File "/root/code/salt/salt/minion.py", line 411, in _thread_return
        ret['return'] = func(*args, **kwargs)
    TypeError: echo() takes exactly 1 argument (0 given)
```

AFTER:
```
(code-salt)salt:~/code/salt # salt salt test.echo
salt:
    Missing arguments executing "test.echo": ArgSpec(args=['text'], varargs=None, keywords=None, defaults=None)
```
Check version using correct user

Version check fails if the correct user is not used (postgres on my system, the user root does not exist). By respecting the runas argument we avoid an error.
Ability to check which arguments is expected from an execution module.

The execution module sys.doc is great, but sometimes it is helpful to
see the full argument specification of a function.
Fix newline in npm.py.

See #3961.
Modified travis config to use salt ppa for requirements