[PATCH 5/7] .travis.yml: Switch to "sudo: false" for faster builds

[Vladimir Panteleev]

Builds not requiring sudo access run in a container, which will have
better performance and less overhead on the Travis infrastructure.

Use the apt addon to install dependencies instead of explicit apt-get
commands.
---
 .travis.yml | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index e297e516..8b71568d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,11 +1,18 @@
 language: c
 
 dist: trusty
-sudo: required
+sudo: false
 
-before_install:
-  - sudo apt-get update -qq
-  - sudo apt-get install dtach libxapian-dev libgmime-2.6-dev libtalloc-dev python-sphinx gdb gpgsm
+addons:
+  apt:
+    packages:
+    - dtach
+    - libxapian-dev
+    - libgmime-2.6-dev
+    - libtalloc-dev
+    - python-sphinx
+    - gdb
+    - gpgsm
 
 script:
   - ./configure
-- 
2.13.3