expose client as a library

- Allows for using localtunnel from code instead of manually invoking
- add tests
- add travis config
- add travis badge

package.json

@@ -12,11 +12,17 @@
     "book": "1.2.0",
     "optimist": "0.3.4"
   },
-  "devDependencies": {},
+  "devDependencies": {
+    "mocha": "1.6.0"
+  },
   "optionalDependencies": {},
   "engines": {
     "node": "*"
   },
+  "scripts": {
+    "test": "mocha --ui qunit -- test",
+    "start": "./bin/server"
+  },
   "bin": {
     "lt": "./bin/client"
   }