Adds .travis.yml for lint pipeline

.travis.yml

@@ -0,0 +1,12 @@
+language: python
+python:
+  - "3.4"
+  - "3.5"
+  - "3.6"
+  # PyPy versions
+  - "pypy3.5"
+# command to install dependencies
+install:
+  - pip install -r requirements.txt
+# command to run tests
+script: pylint bfxapi