Improves ram prompt
Improves ram prompt

For OS X display the sum of Pages free and Pages inactive
For Non BSD use MemAvailable instead of MemFree

dritter/powerlevel9k,shibumi/powerlevel9k,shibumi/powerlevel9k,bhilburn/powerlevel9k,natemccurdy/powerlevel9k,bhilburn/powerlevel9k,rjorgenson/powerlevel9k,dritter/powerlevel9k,rjorgenson/powerlevel9k,natemccurdy/powerlevel9k