Add 2014 to LICENSE
Include license in latexrun script

This makes it legal to copy latexrun by itself into other repositories
(e.g., paper repositories).

Closes #9
Readme tweaks
Add support for -Wall to show all warnings
Clarify hidden warning message using -Wall

Previously, this just said to "use -W" to show hidden warnings.  This
was intended to mean that the user should use -W with the appropriate
arguments to show the warnings, but taken at face value, it suggested
illegal usage.  Fix this by suggesting -Wall.  This is legal usage and
the user can dig deeper into -W if they wish.

Closes #7
Test for underfull hbox warning supression
Rename tests/ to test/

For better consistency with other projects I work on (so I stop cd'ing
to the wrong directory!)
Remove latex.out/ on --clean-all if empty

Closes #10