Add libev dependecny
diff --git a/.travis.yml b/.travis.yml
index 12875de..2d90929 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,6 +14,7 @@
 language: c
 install:
   - sudo apt-get update -qq && sudo apt-get install -y -qq valgrind
+  - if [ x$LWS_METHOD == xlibev ]; then sudo apt-get install -y -qq libev-dev; fi
 script:
   - mkdir build && cd build && cmake $CMAKE_ARGS .. && cmake --build .