Updated apache_module for backward compatible.

[abednarik]

What does this PR do?

What issues does this PR fix or reference?

This introduced a change of functions names that break this module when using Beryllium or older and upgrading to Boron.
Added here a deprecated warning in to order to advice users to migrate to new functions names. Also
documentation updated since was not updated in the original commit.

Previous Behavior

State:

Enable cgi module:
  apache_module.enable:
    - name: cgi

Result:

salt '*' state.highstate
salt:
----------
          ID: Enable cgi module
    Function: apache_module.enable
        Name: cgi
      Result: False
     Comment: State 'apache_module.enable' was not found in SLS 'default'
              Reason: 'apache_module.enable' is not available.
     Started:
    Duration:
     Changes:

Summary for salt
------------
Succeeded: 0
Failed:    1
------------
Total states run:     1

New Behavior

State:

Enable cgi module:
  apache_module.enable:
    - name: cgi

Result

salt:
----------
          ID: Enable cgi module
    Function: apache_module.enable
        Name: cgi
      Result: True
     Comment:
     Started: 20:27:45.885109
    Duration: 91.94 ms
     Changes:
              ----------
              new:
                  cgi
              old:
                  None

Summary for salt
------------
Succeeded: 1 (changed=1)
Failed:    0
------------
Total states run:     1

Tests written?

Tests are already in place for new named: enabled / disabled. Functions added are just wrappers.

[cachedout]

@abednarik Thank you so much for taking the time to fix this. I can't believe I let that change sneak in. I'm glad you're on the case!

[rallytime]

I think that this warning should go until at least Nitrogen to give people a change to switch their states over. I can grab that quickly.

[abednarik]

Thanks both!

Edited: not needed to do another PR.

[rallytime]

@abednarik That's ok! I fixed it in the back-port I did of this change to 2016.3. The Nitrogen change will come through in the next merge-foward. Thanks again!