Add command line tools

Converted the Bio-Formats command line tools to use the SCIFIO API in a
new tools component.

Instead of being a collection of fixed tools, there is now one entry
point (in the SCIFIOTools class), wich each individual tool being a
command (SCIFIOToolCommand). Commands are plugins and can be discovered
dynamically as such.

As part of the tools maven lifecycle (package step) a scifio shell
script and scifio.bat are generated and packaged. Using these scripts
follows github notation, e.g. "scifio show cat.png" runs the show
command on cat.png.

Arguments and parameters are unix-style (-h or --help for example).

Includes Convert, Info, and Show commands (formerly bfconvert and
showinf), and a Help meta-command.

Closes #12.