travis ci: upgrade to trusty, use system cmake

On July 18, Travis upgraded their default build VM
to Ubuntu Trusty. Trusty has cmake 3.5.1, which allows us to
drop our bundled version.

We explicitely set "dist: trusty" to prevent our build jobs
from being routed to an older build VM.

.travis.yml

@@ -1,3 +1,5 @@
+dist: trusty
+
 language: cpp
 
 sudo: true
@@ -18,12 +20,12 @@ env:
    - secure: "KuAAwjiIqkk4vqSX/M3ZZIvQs6edm+tV8IADiklTUYZIFyxu8FgZ6RbDdMD2sef5bNZA1OZhlcbeRtiKff5CfMtvzc607Lg3NUkpi+ShMynWgqS/e0uCMf9ogEJlUiZMxf4juBi7v6DyMl/WV6pAdJmdfHtzcj8GF2mgTfQjkO8="
 
 before_script:
-  - sh ci/install-cmake.sh
   - sudo modprobe fuse
   - mkdir build
   - cd build
-  - ../ci/cmake/bin/cmake --version
-  - ../ci/cmake/bin/cmake ..
+  - cmake --version
+  - cmake ..
+
 
 script:
   - if [ "${COVERITY_SCAN_BRANCH}" != 1 ]; then make && make check ; fi
@@ -47,3 +49,4 @@ addons:
       - fuse
       - libfuse-dev
       - gettext
+      - cmake3

ci/install-cmake.sh

@@ -1,7 +0,0 @@
-set -x
-set -e
-if [ ! -e ci/cmake/bin/cmake ]; then
-  #wget http://www.cmake.org/files/v3.1/cmake-3.1.0-Linux-x86_64.tar.gz
-  tar -xzf ci/cmake-3.0.2-Linux-x86_64.tar.gz
-  mv cmake-3.0.2-Linux-x86_64 ci/cmake
-fi