Update pool and usage models for "free" and "reclaimable" values.
Add more validation for raid levels during new pool creation. Also compute the pool size correctly based on raid choice.
Update data collector to populate free and reclaimable values of pool usage.
update cli to properly print pool usage information.
Merge branch 'master' into issue#335
Merge branch 'issue#335' of https://github.com/schakrava/rockstor-core into schakrava-issue#335
Add a range slider to display share size during share size creation

Display free and reclaimable space in the slider
User can use either the slider or a text box to enter share size
Correct share size validation
Merge branch 'issue#335' of github.com:schakrava/rockstor-core into issue#335
When pool usage information is not available(brand new pool) default free=capacity and reclaimable=0.
use exception context manager in post. Also fix the wrong pool size calculation.
default to None when public_key is not supplied
Display slider value with free, reclaimable and used space

Display the free, reclaimable and used space in the selected pool while
creating a share.
Calculate used space for pools table
Round sizes to 1 decimal place in gb
Calculate correct value for share size if large number entered.
Merge pull request #479 from schakrava/issue#335

Issue#335