Update Linux install commands with more information

[VickyRampin]

Euan Cochrane on twitter made the good point that our installation instructions for Linux are a tad less descriptive than our installation instructions for other OSs.

Things we could add that might help our users:

• An install command that installs everything for ReproZip, ReproUnzip, and all the unpackers
• An install command that installs everything for ReproZip, ReproUnzip, and reprounzip-docker
• An install command that installs everything for ReproZip, ReproUnzip, and reprounzip-vagrant
• An install command that installs everything for ReproZip, ReproUnzip, and reprounzip-vistrails

He also made the point that:

Your table implies "libssl-dev and libffi-dev" are not needed for basic reprozip but are included in the command for installing dependencies

So we might need to take a second look at our table on installation requirements and update, or provide more detail for users underneath it.

[remram44]

I'm not sure what you have in mind here.