Remove note about using a fixed disk.

`vagrant package` command doesn't export the fixed disk.

Relates to 52fb1ab5caed401f6c50a82ae04ad291d746a37b
Use "." instead of "source" for POSIX compliance

"source" doesn't seem to be POSIX compatible. E.g. fails on Ubuntu where
/bin/sh is mapped to dash)
Remove -j option from date command
Merge branch 'shell-compatibility'

GH-11
Blacklist a module that doesn't load VirtualBox

Complains about an SMBus error. Not required so may as well stop
it from loading.
Resize the initramfs to include only what's needed

Should have a mild speed boost on startup and save a few MBs on the
box output.
Correct indentation for code blocks.
Bump VBGA version.
Remove LC_MESSAGES only instead of all locales

LC_TIME is actually still useful for local time zone information.
GH-7
Heredoc looks nicer and is more straightforward.
Reorganise Vagrant SSH key setup.
Set the hostname in the /etc/hosts file.

Provides similar behaviour to when Vagrant sets the hostname in a
`Vagrantfile`. See GH-14
Edit line inline rather than a new line.
More straightforward VBGA mount
GNU sed uses '-r' for extended regexes

Although apparently it still works fine with '-E' yet the man pages
do not mention this compatibility.
\s is neater than [[:space:]]