Remove Travis

* Travis does not support Postgres 10, so we are temporarily removing it

.travis.yml

@@ -1,13 +0,0 @@
-dist: trusty
-language: go
-go:
-  - 1.9
-services:
-  - postgresql
-before_script:
-  - createdb vulcanize
-  - psql vulcanize < migrations/schema.sql
-script:
-  - go test -v ./core/...
-notifications:
-  email: false