README.rst: general misc improvements

 - Updating the introduction with some more details
 - Adding a link to our master slides on google drive
 - Adding a note about copr on Fedora
 - Adding a note about the man page
 - Misc cosmetic changes
Merge pull request #190 from adereis/master

README.rst: general misc improvements
plugins.{json,xunit}: Add missing space in --help

Trivial fix: missing space in a help sentence.

Signed-off-by: Ademar de Souza Reis Jr <areis@redhat.com>
Merge pull request #194 from adereis/master

plugins.{json,xunit}: Add missing space in --help
doc: add a link to our slides to the Introduction
Merge pull request #195 from adereis/master

doc: add a link to our slides to the Introduction
avocado.plugins.xunit: Consider "not found" as error.

In the XML output, we can't use an exclusive attribute "not_found"
for tests that has been not found. So we're going to count
"not found" as error and remove the attribute "not_found".

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #196 from ruda/xunit_updates

avocado.plugins.xunit: Consider "not found" as error.
docs: Add Contribution Guide

Give pointers on how to contribute to the project. Links
to Mailing lists, pointers to the IRC channel and a brief
explanation of the development model.

Signed-off-by: Lucas Meneghel Rodrigues <lmr@redhat.com>