Remove testify/assert dependency for good

.travis.yml

diff --git a/.travis.yml b/.travis.yml
index 3a59818..b2c7a4b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,5 @@
 language: go
 
-install: 
-  - go get github.com/stretchr/testify/assert
-
 matrix:
   include:
     - go: 1.0