Use unhtml module to unescape HTML entities in console output.

This fixes #4. Could be better to ensure that markit
doesn't escape these entities in the first place, but this
should save trying to navigate the codebase in the meantime.
Merge pull request #5 from hughsk/unhtml

Use unhtml module to unescape HTML entities in console output.
README - guidelines
LSOF command
fix typo in "lsof"
Add contribution message
When looking up the tldr page for a command, if it is not found,
prompt the user to contribute a pull request
Merge pull request #6 from jden/master

Add contribution message
0.0.3