Initial addition of fileserver event

This event is intended to "notify" salt that there are changes to the underlying fileserver module. This can be used to (for example) trigger a module sync within the reactor system-- but really you can do whatever you want with it.
Verify proper owner for `pip.installed`. Refs #6912

Added test case which verifies that the owner of the `pip.installed` package is the one provided by `runas`.
`pip.installed` ownership testcase using `user` instead of `runas`. Refs #6912.
If name is empty it should not be parsed for name and version.
Updated test case to install from a requirements file.
Minor formatting fixes.
Merge pull request #6956 from s0undt3ch/issues/6912

Test case for #6912. Bugfix on requirements parsing.
Add `gitfs_base` config option to set base branch

Add the ability to use a branch other than `master` as the base
environment by setting the `gitfs_base` option in the master config
file.

The Problem:
When using both a feature-branch based git workflow and gitfs, then in order
to test changes in the feature-branch, the top file in the master branch
may need to be modified. It is undesirable to change the master branch in order
to test a feature branch.

Intended Use:
This change is intended to allow for a dev/testing/staging environment
with its own salt master to dynamically change which branch to read the
top file from (with a restart of the salt master). E.g., the test salt
master can set its base branch to `feature` -- which has a modified top
file -- in order to test the changes in `feature` without requiring
changes in `master`.
move ssh routines to salt.client, since it is a client system....
import salt.client.ssh now
ref salt.client.ssh
include salt.client.ssh in setup.py
Rename events to match namespacing standards
Merge branch 'develop' of github.com:saltstack/salt into develop

Conflicts:
	salt/fileserver/gitfs.py
Removed salt.ssh from the packages as it was moved to salt.client.ssh
Merge pull request #6927 from jacksontj/develop

Initial addition of fileserver event
Merge pull request #6965 from evinrude/fix_build_post_ssh_fixes

Removed salt.ssh from the packages as it was moved to salt.client.ssh
Merge pull request #6960 from jesusaurus/gitfs/base

Add `gitfs_base` config option to set base branch
remove pylint checks from travis, these are done in jenkins now
Use the running user and default group for symlink ownership

This commit modifies the work done in 77b749d. Instead of using
root:root for the default symlink ownership if no user/group is
specified, the user under which the salt-minion is running is used when
'user' is not sspecified, and the default group of whatever is assigned
to 'user' is used (whether specified directly or derived using the
aforementioned method).