Bug 1218542 - Install language-pack-en-base in ubuntu1204-test image; set LANG/LC_ALL to en_US.UTF-8, r=dustin

Also calls `dpkg-reconfigure locales`, but it's not entirely clear if this is
necessary or not.

testing/docker/desktop-test/Dockerfile

@@ -1,4 +1,4 @@
-FROM          taskcluster/ubuntu1204-test-upd:0.1.1.20151012044301
+FROM          taskcluster/ubuntu1204-test-upd:0.1.2.20151102105912
 MAINTAINER    Jonas Finnemann Jensen <jopsen@gmail.com>
 
 # Add utilities and configuration

testing/docker/desktop-test/VERSION

@@ -1 +1 @@
-0.4.3
+0.4.4

testing/docker/ubuntu1204-test-upd/Dockerfile

@@ -1,4 +1,4 @@
-FROM          taskcluster/ubuntu1204-test:0.1.1
+FROM          taskcluster/ubuntu1204-test:0.1.2
 MAINTAINER    Dustin J. Mitchell <dustin@mozilla.com>
 
 ### update to latest from upstream repositories

testing/docker/ubuntu1204-test-upd/VERSION

@@ -1 +1 @@
-0.1.1.20151012044301
+0.1.2.20151102105912

testing/docker/ubuntu1204-test/Dockerfile

@@ -15,6 +15,8 @@ ENV           SHELL         /bin/bash
 ENV           USER          worker
 ENV           LOGNAME       worker
 ENV           HOSTNAME      taskcluster-worker
+ENV           LANG          en_US.UTF-8
+ENV           LC_ALL        en_US.UTF-8
 
 # Set a default command useful for debugging
 CMD ["/bin/bash", "--login"]

testing/docker/ubuntu1204-test/VERSION

@@ -1 +1 @@
-0.1.1
+0.1.2

testing/docker/ubuntu1204-test/system-setup.sh

@@ -38,6 +38,7 @@ apt_packages+=('gstreamer0.10-plugins-base')
 apt_packages+=('gstreamer0.10-plugins-good')
 apt_packages+=('gstreamer0.10-plugins-ugly')
 apt_packages+=('gstreamer0.10-tools')
+apt_packages+=('language-pack-en-base')
 apt_packages+=('libasound2-dev')
 apt_packages+=('libasound2-plugins:i386')
 apt_packages+=('libcanberra-pulse')
@@ -124,6 +125,8 @@ apt_packages+=('python-pip')
 apt-get update
 apt-get install -y --force-yes ${apt_packages[@]}
 
+dpkg-reconfigure locales
+
 # set up tooltool (temporarily)
 curl https://raw.githubusercontent.com/mozilla/build-tooltool/master/tooltool.py > /setup/tooltool.py
 tooltool_fetch() {