Use json.load() instead of json.loads()

json.load() read data from fp and make code simpler.
Support Leonardo board

Thanks to Bogdan Petrisor <petrisorbogdan@yahoo.com> for this patch.

Conflicts:
	SConstruct
Fix to use getBoardConf() when get vid and pid for leonardo
Add a target, version to print version of arscons

    $ scons -s version
    arscons v1.0.0
Update SConstruct

correction in path of avrdude
Merge pull request #15 from b4zz4/patch-1

Update SConstruct
Fix broken links by using absolute URLs in README
Merge pull request #19 from bergey/master

Fix broken links by using absolute URLs in README
Merge pull request #1 from suapapa/master

update from upstream