Extract env listing code into common for reuse
Add envs command to just show environment information
Fix for spaces in install directory and in env names
Rename command from envs to env per @joelhullcio
Refactor to allow subcommands
Start work on better printing of package version changes
Use new-style string formatting
Align things correctly
Only use as much space as needed
index cannot be None in display_actions anyway, so make it required
Split the display information into four categories

Also add a little more whitespace, for readability
Left-align the versions

It makes them easier to read.
Remove the old package table
Keep a dictionary of Package objects
Add channel information to the installed listing
Get the index for remove if we are showing the channel urls
Show channel information with remove
Allow for no linked or unlinked packages
The Packages dict doesn't use .tar.bz2
Show channel information for updated and downgraded