:bug: [BUG FIX] Shell expansion mangling path.

$$ was used instead of $ in setup-3110 to dereference shell variables.
$$ expanded to the pid of the current shell. This mangled PATH (run diff
to see for yourself).
:book: [DOCUMENTATION] Updated README to markdown.

I changed README.txt to README.md, added fancy formatting, made some
minor edits, and added resources.
[FEATURE] Named VirtualBox VM cs3110-VM.

Previously, the VM created from vagrant up created a long and random
name for the VM. Now, the VM is always named cs3110-VM.