Merge pull request #6831 from s0undt3ch/develop

Fix 'runtests.py', use named tuples from getargspec
Since salt required python >= 2.6 we can use the `getargspec` named tuple.
Merge pull request #6832 from s0undt3ch/features/named-tuples-argspec

Since salt required python >= 2.6 we can use the `getargspec` named tuple
deprecations.rst: fix grammar: it's => its
Merge pull request #6835 from cvrebert/patch-2

deprecations.rst: fix grammar: it's => its
Merge pull request #6837 from s0undt3ch/develop

Don't fail if there's nothing to feed to `max()`.
Fix bug introduced in fcfe3a9 when changing argspec to use the named tuple