Use "$PATH" to avoid weirdness.

Without this, I get this error when gvm is being loaded:

    /home/manveru/.gvm/scripts/gvm-default:export:17: not an identifier: 2:/home/manveru/node_modules/.bin:/home/manveru/github/akunspy/gopbuf/bin:./node_modules/.bin:.
Merge pull request #52 from manveru/patch-1

Use "$PATH" to avoid weirdness.