GitLab

Substitutes the current duplicate logic for the standard
and cross-platform function open_command in plugins:

  frontend-search, jira, node, web-search

The $OSTYPE variable is set at ZSH compile time and can be safely used
to determine the OS of the system. e.g. darwin (os x)

The `#anchor` tags on
[nodejs.org](http://nodejs.org/docs/v0.8.2/api/all.html) changed. This
fixes the `node-docs` command.

sorin-ionescu had some good points.

Add helper function to open node api in browser. Add binaries installed via
npm to path. Tell node where to find things (what things?).