Use travis to set the PATH properly

.travis.yml

@@ -37,6 +37,7 @@ before_install:
 install:
   - bash ci/install.sh
   - export PATH="$PATH:$PWD/qemu"
+  - export PATH="$PATH:$PWD/mdbook-bin"
 
 script:
   - bash ci/script.sh

ci/install.sh

@@ -27,8 +27,6 @@ main() {
     tar -xf mdbook.tar.gz
     mkdir -p mdbook-bin
     mv mdbook mdbook-bin/
-    PATH=$(pwd)/mdbook-bin:$PATH
-    which mdbook
 
     #install_crate mdbook 0.3.1
 }