First commit of Twilio notifications modules

Sending a message via SMS supported to begin with
Merge pull request #12190 from UtahDave/twilio

First commit of Twilio notifications module
rm duplicate import of salt.utils.event in salt.client.ssh

************* Module salt.client.ssh
salt/client/ssh/__init__.py:35: [W0404(reimported), ] Reimport 'salt.utils.event' (imported line 31)
Merge pull request #12191 from cvrebert/patch-1

rm duplicate import of salt.utils.event in salt.client.ssh
Change user salt configs to .saltrc from .salt to prevent conflicts
client.ssh.wrapper.state: rename local vars to avoid shadowing

************* Module salt.client.ssh.wrapper.state
salt/client/ssh/wrapper/state.py:39: [W0621(redefined-outer-name), sls] Redefining name 'high' from outer scope (line 118)
salt/client/ssh/wrapper/state.py:287: [W0621(redefined-outer-name), show_sls] Redefining name 'high' from outer scope (line 118)
salt/client/ssh/wrapper/state.py:314: [W0621(redefined-outer-name), show_top] Redefining name 'top' from outer scope (line 189)
Merge pull request #12193 from hulu/ssh-wrapper-state

client.ssh.wrapper.state: rename local vars to avoid shadowing
Merge pull request #12194 from basepi/saltrc12169

Change user salt configs to .saltrc from .salt to prevent conflicts
Don't fire events on module refresh with --local

Closes #12173

Use .get()
Add function to delete a minion cache with relative safety.
Merge pull request #12195 from cachedout/12173

Don't fire events on module refresh with --local
Pylint
Remove unused "ports" argument from docker.start
Merge pull request #12197 from cachedout/6947

Add function to delete a minion cache with relative safety.
Merge pull request #12198 from terminalmage/issue11990

Remove unused "ports" argument from docker.start
Fix S3 module docs.

Closes #12199
Split up contributing/development docs

This page has become massive and merits being split into two pages.
Also, it affords the opportunity of getting rid of an ambiguous header
name that causes confusion.

Fixes #10830.
Merge pull request #12202 from cachedout/12199

Fix S3 module docs.
Merge pull request #12204 from terminalmage/docs

Split up contributing/development docs
Add backing if vgname is defined