TST: remove references to Travis. Fix conda tests. (#234)

* TST: remove references to Travis. Fix conda tests.

Removes the last references to Travis from the README and configuration
files.

I've attempted to fix the conda build by updating the null floats test
to have at neast 1 non-null value.

* fix null float test.

Author: tswast

.travis.yml

@@ -37,8 +37,8 @@ Usage
 
 See the `pandas-gbq documentation <https://pandas-gbq.readthedocs.io/>`_ for more details.
 
-.. |Build Status| image:: https://travis-ci.org/pydata/pandas-gbq.svg?branch=master
-   :target: https://travis-ci.org/pydata/pandas-gbq
+.. |Build Status| image:: https://circleci.com/gh/pydata/pandas-gbq/tree/master.svg?style=svg
+   :target: https://circleci.com/gh/pydata/pandas-gbq/tree/master
 .. |Version Status| image:: https://img.shields.io/pypi/v/pandas-gbq.svg
    :target: https://pypi.python.org/pypi/pandas-gbq/
 .. |Coverage Status| image:: https://img.shields.io/codecov/c/github/pydata/pandas-gbq.svg

README.rst

@@ -16,11 +16,7 @@ def project_id():
 @pytest.fixture(scope="session")
 def private_key_path():
     path = None
-    if "TRAVIS_BUILD_DIR" in os.environ:
-        path = os.path.join(
-            os.environ["TRAVIS_BUILD_DIR"], "ci", "travis_gbq.json"
-        )
-    elif "GBQ_GOOGLE_APPLICATION_CREDENTIALS" in os.environ:
+    if "GBQ_GOOGLE_APPLICATION_CREDENTIALS" in os.environ:
         path = os.environ["GBQ_GOOGLE_APPLICATION_CREDENTIALS"]
     elif "GOOGLE_APPLICATION_CREDENTIALS" in os.environ:
         path = os.environ["GOOGLE_APPLICATION_CREDENTIALS"]

ci/travis_encrypt_gbq.sh

@@ -297,14 +297,16 @@ def test_should_properly_handle_nullable_doubles(self, project_id):
         )
 
     def test_should_properly_handle_null_floats(self, project_id):
-        query = "SELECT FLOAT(NULL) AS null_float"
+        query = """SELECT null_float
+        FROM UNNEST(ARRAY<FLOAT64>[NULL, 1.0]) AS null_float
+        """
         df = gbq.read_gbq(
             query,
             project_id=project_id,
             credentials=self.credentials,
-            dialect="legacy",
+            dialect="standard",
         )
-        tm.assert_frame_equal(df, DataFrame({"null_float": [np.nan]}))
+        tm.assert_frame_equal(df, DataFrame({"null_float": [np.nan, 1.0]}))
 
     def test_should_properly_handle_timestamp_unix_epoch(self, project_id):
         query = 'SELECT TIMESTAMP("1970-01-01 00:00:00") AS unix_epoch'