PEP-8 whitespace changes
Add comp, concat, concatv, mapcat, cons and interpose, with tests.
Address PR comments
Fix xrange / range compat. issue

For Py2.x in test_core, use range everywhere but redefine in
compatibility, as requested.
Add 'see also' to docstring for concat
Add 'see also' to docstring for concat [fix typo]
Tweak docstring for concat
Fix build indicator for TravisCI

mrocklin->pytoolz
add imap to compatibility
add range to py3 compatibility
minor docstring changes
add test and import for cons
Fix broken Python3 tests

Needed imap substitution for Py3.
Merge remote-tracking branch 'matt/eigenhombre-1'

Conflicts:
	itertoolz/compatibility.py
PEP-8
Remove duplicate lines
Merge pull request #2 from eigenhombre/master

Add several sequence functions