fix: path to cucumber binary

`__dirname` was causing the path to resolve relative to `./node_modules/gulp-cucumber` instead of `./`. Since gulp is always run from the project's root directory, it makes sense to use `process.cwd()` to avoid any confusion.
feat: add support for glob-matched step files and fix error when cucumber already installed
fix: output formatting
feat(file-matching): use simple-glob for better file matching
style: clean up some verbose code
style: concise binary path resolution
feat: add support for `support` files
feat: add `support` property to config, for support files
feat: add `support` property to config, for support files
feat: add `support` property to config, for support files
fix typoin readme and index.js
Merge pull request #6 from tathata/master

fix: path to cucumber binary