Update recipes/pip.rb

/usr/bin/ is not pip_binary location when doing a source install on rhel.
COOK-1925: Support SmartOS for python
[COOK-1715] Upgrade pip resource with user & group

- pass user & group to shellout
- refactor provider to remove lots of duplication
- also set HOME to specified user's home to prevent permission errors
  when pip attemts to write ~/.pip/pip.log
Merge branch 'COOK-1715'
release v1.1.0
Merge pull request #24 from wohali/master

COOK-1925: Support SmartOS for Python
Merge pull request #23 from tdcarrol/master

[COOK-1866] /usr/bin/ is not pip_binary location when doing a source install on rhel.
release v1.2.0
[COOK-2297] more gracefully handle pip packages from VCS or source archives
Merge pull request #28 from Frick/master

[COOK-2297] more gracefully handle pip packages from VCS and source archives
Use :install as the default action
also look for https
release v1.2.2
Truly support backwards compatability
Merge pull request #29 from sethvargo-cookbooks/COOK-2376-python_pip_default_action

Use :install as the default action for python_pip
[COOK-2449] Make the distribute download location an attribute

Add attributes to define the location of the distribute install script and the
package location. This allows independence of external sources that when down,
cause installation of distribute to fail.
Break up distribute_options_download_base attribute

Change the `distribute_options_download_base` attribute to
`['distribute_options']['download_base']`.
[COOK-2468] set precedence level when setting node attributes

This fixes the `Chef::Exceptions::ImmutableAttributeModification` which 
is thrown when run on Chef 11+
fixes for [FC002] - Avoid string interpolation where not required
fixes for [FC016] - LWRP does not declare a default action