Support pyvenv in virtualenv module
Fix mod_watch for supervisord state

The "update" param was not being taken into account by mod_watch,
causing parameters to be passed in the wrong order and ignoring the
"update" param altogether. This commit corrects that.

Fixes #6021.
Merge pull request #6028 from terminalmage/issue6021

Fix mod_watch for supervisord state
Merge pull request #6026 from extesy/patch-1

Support pyvenv in virtualenv module
Document defining custom grains in /etc/salt/grains
Merge pull request #6032 from terminalmage/docs

Document defining custom grains in /etc/salt/grains
Do not specify "name" when using pip install --editable

This fixes #6025 by setting "name" to an empty string if the "editable"
param is used, like is already being done for the "requirements" param.
Merge pull request #6037 from terminalmage/issue6025

Do not specify "name" when using pip install --editable
Pass __env__ to salt.modules.pip._get_cached_requirements

This fixes #6003, and resolves a traceback caused by the environment not
being passed to the function.
Merge pull request #6043 from terminalmage/issue6003

Pass __env__ to salt.modules.pip._get_cached_requirements