Update the Makefile and build-site.py to notify of missing dependencies

fix ansible-playbook manpges regarding option for syntax check

Fixes #2287.

Update mysql_db

The target parameter is not required, the DOCUMENTATION section was in error.

Allow 'make rpm' without the need for env-setup

get_url: should always download the file when force is set

add docs to mount module using LABEL and UUID

Fixes #2305.

No reason to build the website for RPMs/DEBs, adding dependency on
Sphinx.

Corrected formatting in docs for the gem-module

As it used to be before, 'make rpm' from a cloned repository should work without the need to run hacking/env-setup. It's an easy fix, in line with what we already did for the man-pages.

Fixes #2280.

Revert "Revert "for #2196 now gruopby module invalidates host cached variables so they can be reevaluated with new groups""

This reverts commit dc0515a8.

We didn't need to revert this :)

Revert "for #2196 now gruopby module invalidates host cached variables so they can be reevaluated with new groups"

This reverts commit 2d86671a.

Fixes #2277.

Update get_url

Not quite as attractive, but allows variable precedence and lazy
resolution to work as intended, rather than resolving them on a
per-inventory basis.

Small syntactic correction: Removed trailing double-quote from example.

now ansible shows nice message about missing json instead of traceback

Added tip about ANSIBLE_KEEP_REMOTE_FILES to docsite

Signed-off-by: Brian Coca <briancoca+dev@gmail.com>

Signed-off-by: Brian Coca <briancoca+dev@gmail.com>

Fixed a small buglet, if using with_items with yum and so on, only optimize the package list if the package list is all strings

now group by module invalidates host cached variables