check for setup/uninstall script compatibility on osx

[GiselleSerate]

Please do the following when you get access to a lab mac:

• setup works!
• uninstall works!
• documentation for this process written!
• check src command works for mac, or at least fails gracefully? (it does not. this is the wrong file to source.)

[aryarm]

Also, cds needs to be tried on a lab mac.
And also some of the code in .bash_nav. The windows aliases shouldn't be available on a mac.

[GiselleSerate]

cds is gucci on a mac, but apparently altalias is . . . bad. Not good. Has error, but works.
Error:

computer:~ gserate$ alias -s srenv='source .env/bin/activate'
expr: syntax error
Creating new permanent alias: alias alias='altalias'
alias serve='php artisan serve &>/dev/null &'
alias srenv='source .env/bin/activate'