Only Syndic minions have .local; push .local cleanup down into Syndic class

************* Module salt.minion
E1101:1126,16:Minion.destroy: Instance of 'Minion' has no 'local' member
minion.py: caps in comments
Merge pull request #6019 from cvrebert/patch-1

minion.py: caps in comments
Merge pull request #6018 from cvrebert/syndic-local-pylint

Only Syndic minions have .local; push .local cleanup down into Syndic class
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
Try to narrow down used fds. Refs #5878.
Fix mode in salt.modules.file.mkdir()

This removes the last remaining octal-specific code from the file
module. Fixes #6033.
Merge pull request #6046 from terminalmage/issue6033

Fix mode in salt.modules.file.mkdir()
Merge pull request #6044 from s0undt3ch/issues/5878-file-descriptors-leak

Try to narrow down used fds. Refs #5878.