[ospec] feat: nicer binary with support for globs (#2141)

* feat(ospec): CLI support for file-patterns and an --ignore flag

The added dependency is only used by the node.js binary - which normally only ever installed via npm/yarn anyway.

This does not interfer with ospec proper being dependencyless.

* chore(mithril): Add glob dependency needed by the ospec binary

this is only needed while ospec is inlined in the
mithril repo. As soon as ospec is split away into a
standalone npm module, this will not be required anymore.

* refactor(ospec): Use 'match' events instead of callback

Performance should be similar, but the code looks
cleaner and easier to grok.

* Misc tweaks

package.json

@@ -32,6 +32,7 @@
     "dedent": "^0.7.0",
     "eslint": "^3.19.0",
     "gh-pages": "^0.12.0",
+    "glob": "^7.1.2",
     "istanbul": "^0.4.5",
     "lint-staged": "^4.0.4",
     "locater": "^1.3.0",