Some minor documentation enhancements.
Merge pull request #1112 from pelson/docs_tidy

DOC: Minor documentation enhancements.
making in-place addition modification suggested in issue #1089
Merge pull request #1116 from rebeccaroisin/inplace_addition

Speed-up through in-place addition (closes gh-1089)
 Website font readability improvements.

 Increase font size by 1%
 Increase character spacing
 Increase font size in code snippets to website standard
Merge pull request #1121 from Cadair/doc_theme_tweaks

 Website font readability improvements.
Fix #1108
Merge pull request #1124 from blink1073/master

Fix import when not built (closes gh-1108)
Fix matplotlib install, make installs verbose, add spacers
Fix typo in spacer declaration
Merge pull request #1128 from blink1073/fix-travis

Fix travis build for python 3.2
Add mask option to exposure.equalize_hist with test.

Remove print and fix comparision to None

Update test to make it clear there is a difference

Fix mask logic and `equalize_hist` in `__all__`.

Fix handling of mask and tweak mask test

Another run at travis

Update travis to avoid conflict