use node-glob instead of wildcard for better pattern support

node-glob is located here: <https://github.com/isaacs/node-glob>
It supports common filename glob patterns, including patterns
like: `'**/*.js'`.  This commit allows vows to be called, for
example, like this: `vows --spec '**/test-*.js'`.
Merge pull request #267 from coltrane/glob

use node-glob instead of wildcard for better pattern support