Fix cc4374a to work on all types.

Also adds some code comments
See #15

index.js

@@ -25,8 +25,15 @@ module.exports = compressible
 
 function compressible(type) {
   if (!type || typeof type !== "string") return false
+
+  // Strip charset
   var i = type.indexOf(';')
   if (~i) type = type.slice(0, i)
-  var mime = db[type.toLowerCase().trim()]
+
+  // handle types that have capitals or excess space
+  type = type.trim().toLowerCase()
+
+  // attempt to look up from database; fallback to regex if not found
+  var mime = db[type]
   return mime ? mime.compressible : /^text\/|\+json$|\+text$|\+xml$/.test(type)
 }

test/test.js

@@ -6,10 +6,11 @@ var compressible = require('../')
 var example_types = [
   { type: 'text/penguins', should: true },
   { type: 'something/text', should: false },
-  { type: 'something/frog+text', should: true },
-  { type: 'type/json', should: false },
+  { type: 'something/frog+TEXT', should: true },
+  { type: 'type/json;askjkl+json', should: false },
   { type: 'type/+json', should: true },
-  { type: 'data/beans+xml', should: true },
+  { type: 'data/beans+xml ; charset="utf-8"', should: true },
+  { type: 'can/worms+xml;blaaaah', should: true },
   { type: 'data/xml', should: false },
   { type: 'asdf/nope', should: false },
   { type: 'cats', should: false }