implement EnsureDevtools and RInstall
work with aliases
implement InstallDeps
call InstallDeps
add more aliases
need to use Exec
pretty-print PATH
Merge branch 'master' into deps
re-implement InstallDeps and everything necessary for it in PowerShell
Merge branch 'deps'
use build_script for installing dependencies and test_script for building and testing package
update sample
Merge branch 'master' into r-travis-stable

Conflicts:
	appveyor.yml
Merge branch 'r-travis-stable' into r-travis