Merge pull request #5 from cboettig/master

Treat the --deps arg as a boolean, not a string [bugfix]
Merge pull request #6 from cboettig/master

installGithub also needs to handle logical, NA and string arguments to --deps.
minor post-processing of install2 after Carl's pull request
Merge branch 'master' of github.com:eddelbuettel/littler
clean up temp. rds files in, add copyright headers in install*r and update.r