no sudo in travis.yml and add rocks installer

.travis.yml

@@ -8,7 +8,5 @@ compiler:
 script: make WITH_LUA=1 WITH_DEBUG=1 WITH_IPV6=1 WITH_WEBSOCKET=1
 
 before_install:
-  - sudo apt-get update
   - bash .travis/setup_lua.sh
-  - sudo luarocks install lunitx
-  - sudo luarocks install lua-curl
+  - bash .travis/install_rocks.sh

.travis/install_rocks.sh

@@ -0,0 +1,13 @@
+#!/bin/bash
+
+set -e
+
+LUAROCKS=$TRAVIS_BUILD_DIR/build/lua/bin/luarocks
+PATH=$($LUAROCKS path --bin):$PATH
+LUA_PATH=$($LUAROCKS path --lr-path)
+LUA_CPATH=$($LUAROCKS path --lr-cpath)
+
+$LUAROCKS install lunitx
+$LUAROCKS install lua-curl
+
+