Adding coverage to .npmignore, Slack notifications / supported node versions to Travis file and badges to Readme

Author: corymsmith

.npmignore

@@ -7,3 +7,4 @@ src/
 test/
 !lib/
 .github/
+coverage

.travis.yml

@@ -13,4 +13,9 @@ addons:
 before_script:
   - npm install -g codeclimate-test-reporter
 after_script:
-  - codeclimate-test-reporter < coverage/lcov.info
+  - codeclimate-test-reporter < coverage/lcov.info
+notifications:
+  email: false
+  slack:
+    rooms:
+      secure: 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

README.md

@@ -5,6 +5,7 @@
 [![Test Coverage](https://codeclimate.com/github/feathersjs/feathers-primus/badges/coverage.svg)](https://codeclimate.com/github/feathersjs/feathers-primus/coverage)
 [![Dependency Status](https://img.shields.io/david/feathersjs/feathers-primus.svg?style=flat-square)](https://david-dm.org/feathersjs/feathers-primus)
 [![Download Status](https://img.shields.io/npm/dm/feathers-primus.svg?style=flat-square)](https://www.npmjs.com/package/feathers-primus)
+[![Slack Status](http://slack.feathersjs.com/badge.svg)](http://slack.feathersjs.com)
 
 > The Feathers Primus real-time API provider