Improve getting started documentation

This patch adds more explicit documentation on system level dependencies
and project level dependencies.
Fix rake and thor not working with bundler

Without this patch I'm getting the following errors.  This patch addresses the
problem by specifying rake and thor as a project dependency.

    /usr/bin/rake:35:in `require': cannot load such file -- rake (LoadError)
        from /usr/bin/rake:35:in `<main>'

And for thor:

    rake aborted!
    cannot load such file -- thor
    /work/razor-el-mk/Rakefile:1:in `require'
    /work/razor-el-mk/Rakefile:1:in `<top (required)>'
    (See full trace by running task with --trace)
(RAZOR-145) Add dmidecode (and virt-what) to microkernel

Without this patch the microkernel 004 release includes `dmidecode`, but
the build automation tools do not explicitly express a dependency on
dmidecode.  This is a problem because it is not clear there is a
requirement to always include `dmidecode` in the microkernel.  If this
requirement is not met for some reason in the future key facts may be
omitted.

This patch addresses the problem by explicitly adding dmidecode to the
kickstart configuration for the microkernel in an effort to ensure the
executable is always present for use with facter.

In addition, virt-what is added since this tool helps provide more
accurate virtualization fact support and so this dependency is
explicitly listed in the kickstart configuration.