_slot_operator_update_probe: fix bug #508762

This fixes the check_reverse_dependencies function (inside the depgraph
_slot_operator_update_probe method) to account for irrelevant parent
atoms from parents that need to be rebuilt or have been involved in
unsolved slot conflicts.

X-Gentoo-Bug: 508762
X-Gentoo-Bug-URL: https://bugs.gentoo.org/show_bug.cgi?id=508762
Reviewed-by: Brian Dolbec <dolsen@gentoo.org>
QA: Add a set of checks for bash-completion files

Add checks for common mistakes when installing bash completion files:
legacy directory, incorrect naming, missing aliases, deprecated 'have'
function.

Acked-by: Brian Dolbec <dolsen@gentoo.org>
self-update: Copy only relevant packages from PORTAGE_PYM_PATH

Update the self-update code to copy only packages relevant to Portage,
to avoid copying other packages when Portage is installed alongside
them.
portage.const: Make PORTAGE_PYM_PATH point to the real package tree

Change PORTAGE_PYM_PATH to use real package tree path rather than one
based on PORTAGE_BASE_PATH.
tests: Append .py to files that need to be installed

Append .py to the runTests script and __test__ files so that they could
be easily picked up by setup.py.
tests: Fix running on installed copy of Portage
Install Portage using setup.py
travis: Use setup.py for running tests