factor.rb: added path_environment_variable

Closes #7772
Merge pull request #7790 from vitorgalvao/factor-path

factor.rb: added path_environment_variable
Update sloth license from unknown to gpl

http://sveinbjorn.org/sloth
Update rstudio license from unknown to affero

see https://github.com/rstudio/rstudio/blob/master/COPYING
Update r license from unknown to gpl

See https://svn.r-project.org/R/trunk/doc/COPYING and https://svn.r-project.org/R/trunk/doc/COPYRIGHTS
Update multibit license from unknown to mit

See https://multibit.org/
Update controlplane license from unknown to gpl

See https://github.com/dustinrue/ControlPlane/blob/master/COPYING.txt
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See http://colloquy.info/project/wiki/Source%20Code
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Trial expires after tenth launch
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Limits cleaning until purchase
Update libreoffice license from unknown to oss

Licensed under mpl but includes software with many licenses, including gpl