we don't use travis for tests; remove .travis.yml

.travis.yml

@@ -1,31 +0,0 @@
-sudo: false
-language: python
-python:
-    - '2.7'
-env:
-    - TOXENV=api-lint
-    - TOXENV=api
-    - TOXENV=ui-lint
-    - TOXENV=ui
-install:
-    - pip install tox
-script:
-    - tox
-# after_success:
-#     - TOXENV=coveralls tox
-addons:
-    apt:
-        packages:
-            - swig
-            - libxmlsec1-dev
-            - postgresql-9.5
-            - libssl-dev
-cache:
-    pip: true
-    directories:
-        - node_modules
-        - .tox
-services:
-    - mongodb
-    # Enable when we stop using sqlite for API tests
-    # - postgresql