build: modify travis to not use sudo

.travis.yml

@@ -1,13 +1,14 @@
+sudo: false
 dist: trusty
-
 language: c
 
-before_install:
-  - sudo add-apt-repository -y ppa:team-gcc-arm-embedded/ppa
-  - sudo apt-get update
-
-install:
-  - sudo apt-get install -y build-essential gcc-multilib gcc-arm-embedded
+addons:
+  apt:
+    packages:
+    - build-essential
+    - gcc-multilib
+    - gcc-arm-none-eabi
+    - libnewlib-arm-none-eabi
 
 script:
   - make vendorheader