CLN: Python 3.4 deprecation of assert_

#7131: replace instances of assert_(not b) with assertFalse(b) and some instances of assert_(b) with assertTrue(b). Work-in-progress
BUG: hashtable memory error causes test_factorize_nan crash
BUG: PeriodIndex slices with out of bounds results incorrect
Merge pull request #7161 from sinhrks/pslice2

BUG: PeriodIndex slices with out of bounds results incorrect
Merge pull request #7162 from bwignall/issue7131_assert

CLN: Python 3.4 deprecation of assert_
CLN: Deprecation of assert_

#7131: Convert more instances of self.assert_(not b) to self.assertFalse(b) and self.assert_(b) to self.assertTrue(b)
Merge pull request #7164 from bwignall/issue7131_assert2

CLN: Deprecation of assert_
Merge branch 'hashtable' of https://github.com/mtkni/pandas into mtkni-hashtable

Conflicts:
	doc/source/release.rst
CLN: Deprecation of assertEquals

#7131: s/self.assertEquals(/self.assertEqual(
Merge pull request #7165 from bwignall/issue7131_assertEquals

CLN: Deprecation of assertEquals
CLN: Deprecation of assertAlmostEquals

#7131: s/self.assertAlmostEquals(/self.assertAlmostEqual(
Merge pull request #7166 from bwignall/issue7131_assertalmostequals

CLN: Deprecation of assertAlmostEquals
CI: use current versions for excel / dateutil / pytz on 3.4 build
Merge pull request #7170 from jreback/new

CI: use current versions for excel / dateutil / pytz on 3.4 build
CLN: Deprecation of assert_

#7131: Run s/self.assert_(/self.assertTrue( on remaining instances I can find. These were the multi-line expressions, and I tried to retain the formatting of the expressions
CLN: Deprecation of assert_

Fix formatting of one multi-line assertion, from assert_ --> assertTrue cleanup
Merge pull request #7172 from bwignall/issue7131_assert_

CLN: Deprecation of assert_
BUG: fix isnull for 0d object arrays
Merge pull request #7176 from shoyer/isnull-0d-object-array

BUG: fix isnull for 0d object arrays
BUG: tzinfo lost when concatenating multiindex arrays