Merge pull request #75 from RevolutionAnalytics/dev

Dev
updated readme with git2r install
Use relative paths to avoid rsync problems (related to #80)
Added additional messages for tracing and debugging
Fixed typos in MRAN-update.bsh and accounting.bsh
reverted back to using roxygen2 cran version, more likely everyone will have that
Merge branch 'master' of github.com:RevolutionAnalytics/RRT
added startup.R file to add pkg startup message, and write env variable for mran url, #82
fixed spelling error in pkg startup message
all mran_* functions now use the environment variable to construct urls, #82
changed mran_set fxn to read envir variables for mran url, #82
pkgs_mran now uses system variable for mran url #82
changed url references to marmoset... url to mran... url, #82
added rrt_repos_remove fxn to remove any RRT repos that have been removed by user from global list
closes #76, closes #79
moved around print message for rrt_repos_remove, #76, #79
bumped path ver number and date