Copy raw unicode characters and html entities

By adding draggable="false" to the <img> tag it'll make newer browsers
copy the content in alt="" to the clipboard when the <img> tas has been
selected.

Also added in default conversion of HTML entities into their unicode
equivalents and output as images.
Add test for unicode character as alt text
Make the img tag configurable
Tests for replacing HTML entities for unicode
Unicode as alt as a configuration point
Add Author and Changelog entry
Unicode narrow support

This update should take care of emojis encoded in unicode surrogate pairs.
Merge branch 'feature/unicode-narrow-support' into develop
Documentation update and prepare for 1.2

Closes #11.
Add template tag for replace_html_entities

Closes #10
Don't use skipIf as it's not available on 2.6
Add in coveralls to Travis build
Add coverage options
More lines for coverage to ignore

These lines are hit by python version or if the test suite is being run
from django. So they are to ensure that things continue to work at weird
configurations that I haven't found how to test on Travis.