Make the specs pass.

Fix some trailing-newline issues and remove specs for the now-removed
uninstall_last_package method.
Remove dependency on Rugged.
Have 'Aggressive' be the default for Active Texture Management.
KAS is now hosted on nabaal.net
Update the download URL for Remote Tech 2.
Handle case of there not being a good config file present.
Make sure git ignores nothing.
Add patches and aliases for Kerbal Engineer Redux.
Add a package for VOID.
Add a package for the ModZero patch for B9.
Add support for a download cache.

This is helpful when I want to avoid having to hit external downloads, because
I'm running into some issues with sites throttling me.

This is a development feature, not meant to be used by end users. Most users do
not download packages repeatedly, but those who are testing their downloads
will.
CLI: Handle case of user not supplying what to uninstall.
Open config file with mode r+.

Otherwise, we won't be able to read the file before writing to it, which causes
issues with maintaining existing contents of the file.
Add a package for Hullcam VDS.