add Travis configuration
install ggplot2 and graphviz in Travis build environment
fix travis stall
update package lists from PPA
Travis fixes

- install texlive
- don't pre-install Maven dependencies
install R directly from CRAN
fix r-base-dev install line
use sudo to install R deps
Update README with build status [skip ci]
Move build status marker [skip ci]
Add .gitignore [skip ci]

Conflicts:
	.hgtags
Move archetype tests to shell script for Travis (#362)
Push snapshots to Sonatype (#362)
Add disk stats to build
Remove bashism from archetype script
make deploy script executable
Clean up integration test POM
Add Maven site build
Update README links [skip ci]
actually parse LensKit version