add test for multiple class names

don't append class names that is the empty string
added render_tag function to unit test print_tag
test_id_with_dot_and_hashi & render_tag ->  render

self.assertEqual('%div{id:"foo.bar"}', tohaml.render("<div id='foo.bar'></div>"))
self.assertEqual('%div{id:"foo#bar"}', tohaml.render("<div id='foo#bar'></div>"))
test no tag for div if class or id present
test self closing tag, inline text, attributes

inline text is currently rendered with a newline after the tag
surrounding the text. should be fixed later
test_class_with_dot_and_hash
add python gitignore

current: https://raw.githubusercontent.com/github/gitignore/master/Python.gitignore
version: https://github.com/github/gitignore/blob/c70e357bfde8a842faca6574f1dfc6ad416dfc2a/Python.gitignore
move render into test_helper

the render function was not part of the core library, and has been moved
to test_helper for better abstraction.
added bs4 parser param
Merge branch 'add-tests' from github.com/davidtingsu:add-tests