Stop testing py35 with cryptography master (#958)

diff --git a/.travis.yml b/.travis.yml
index 911ccef..a70fbdd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -32,8 +32,6 @@
   # Also run the tests against cryptography master.
   - python: "2.7"
     env: TOXENV=py27-cryptographyMaster
-  - python: "3.5"
-    env: TOXENV=py35-cryptographyMaster
   - python: "3.6"
     env: TOXENV=py36-cryptographyMaster
   - python: "3.7"
@@ -89,7 +87,6 @@
   # cryptography changes that are beyond our control.
   allow_failures:
   - env: TOXENV=py27-cryptographyMaster
-  - env: TOXENV=py35-cryptographyMaster
   - env: TOXENV=py36-cryptographyMaster
   - env: TOXENV=py37-cryptographyMaster
   - env: TOXENV=py38-cryptographyMaster