rewrote 1.x section of precedence to prevent promissing specificity to those reading docs for earlier versions

made new sections for vars, started explaining scope, gave example on command line override of connection vars
added some formatting changes and clarifications

The _ssh variants will continue to work, but the shorter, more generic
names are preferred now.

Fix #9971, based on text from Paul Czarkowski

This filter was made because I needed to create idempotent UUIDs when
installing the agent for Go (http://go.cd), which uses UUIds to
distinguish the agents from each other.

It uses a newly created Ansible namespace to distinguish UUIDs created
by Ansible from any other source. The new namespace is a random one
created by uuidgen on OSX.

documented new hashing filters and preexisting hashing filters
removed extra sha1 example in others, clarified some of the hashing examples

already

would require extra modules on target.

There is some kind of duplicated content with http://docs.ansible.com/faq.html#how-do-i-loop-over-a-list-of-hosts-in-a-group-inside-of-a-template and this gotcha isn't listed here.

As requested at request pull #9213, I'm proposing updathing this doc. Do you have man pages where I can update this too ?

Thanks

Users will often be puzzled why 'regex_replace' is not working as intended when used inside
YAML arguments. This note explains what they have to do to get it working.

very small and minor addition, but I couldn't find anywhere that answered this (now obvious) question I had of whether or not facts could also be yaml files.