Explicitly pull from 'origin/master'
First draft of new implementation
Implement snapshot feature

Allow one to take a "snapshot" of currently installed plugins.
Complete first draft of snapshot and bootstrap
Fix bug when calling say function
Update codebase

Enforces a more modular approach.
Update libexec/vpm-version

Uses convention for variable name as with the other commands.
Make sure required arguments are present
Ensure that pathogen.vim is installed
Make sure file exists before bootstrapping
Update README.md
Update usage instructions
Make VPM_LIBEXECDIR a placeholder value
Use `command -v` instead of `which`.

See http://mywiki.wooledge.org/BashFAQ/081.