Resolve #3: Add memory management configuration.

Configures vagrant to use 1/4 system memory for the VM.
Resolve #3: Add system mem local override ability.
Merge pull request #36 from gabesullice/e3

Resolve #3: Add memory management configuration.

That looks better, I like that you are choosing a sensible default but still give the user power to decide if they want to bump up their own vm memory.