massive cleanup of very simple tags that don't add much value anyway

Fixes #41 .
I've done a massive cleanup of all the tags that can be now inserted just by doing

t TAB
or
tn TAB (in case of newline).

I still suggest emmet-mode to work with HTML which is a better choice probably, anyone if anyone doesn't agree please let me know, otherwise I will merge this PR in a few days.
Thanks