parser: add method for asserting valid build file

Signed-off-by: Alberto Corona <alberto@0x1a.us>
parser: remove verbose print file extension

Signed-off-by: Alberto Corona <alberto@0x1a.us>
parser: add error on invalid build file

Signed-off-by: Alberto Corona <alberto@0x1a.us>
travis: test -p option

	- Test with both valid and invalid file

Signed-off-by: Alberto Corona <alberto@0x1a.us>
yabs: add -p option

	- The -p option can be used to verbosely parse a configuration
	  file

Signed-off-by: Alberto Corona <alberto@0x1a.us>
parser: fix return on {Close,Parse}Config

Signed-off-by: Alberto Corona <alberto@0x1a.us>
dist: add extract

	- Will be used to be able to distribute tarballs on releases
	  either defined through a configuration file or through git
	  tags
	- Add license to these files, others in next commit

Signed-off-by: Alberto Corona <alberto@0x1a.us>
LICENSE: add license to files

Signed-off-by: Alberto Corona <alberto@0x1a.us>
travis: add libarchive-dev

Signed-off-by: Alberto Corona <alberto@0x1a.us>
travis: add test for extract

Signed-off-by: Alberto Corona <alberto@0x1a.us>
yabs.pro: add -larchive, dist to yabs qmake profile

Signed-off-by: Alberto Corona <alberto@0x1a.us>
interface: add long options

Signed-off-by: Alberto Corona <alberto@0x1a.us>