#13 Define build Dir location

[dbareis]

Hi,

Just like you can define the location of the "dist" dir, I'd
like to be able to specify the "build" directory.

It would also be great, if there was a "reset" option so
that both of these directories are cleared (removed) to
start "clean". For example if you try a few options
the "dist" directory actually ends up containing "extra"
unwanted files which were not build on the LAST
attempt.