Deal intelligently with dirty/stale packages in lib during snapshot/restore
Remove library.old folder during startup
Fix bug: packrat can't find sources for packages in local repos (#10)
Fix bug: dependency information for manually specified source packages should be calculated from those packages' DESCRIPTIONS, not from installed packages
Always install packages in dependency order (#11)
Provide a means to suppress prompts in ::snapshot() and ::restore()

Conflicts:
	R/install.R
	R/packrat.R
	R/snapshot.R
Fix bug: restore() doesn't check correct package db when used externally

Conflicts:
	R/install.R
Merge remote-tracking branch 'origin/master' into packrat-tests

Conflicts:
	R/install.R
	R/packrat.R
	R/snapshot.R