Add diffutils to travis.yml and install_dependencies

It has been required for a while now, and now actually checked in
the makefiles. Before, if you didn't have it installed it would
just recompile everything.

The readme hasn't been updated to reflect this, I think we need
to go through that separately, and see what's really needed. Or
just instruct people to run the batch scripts.

.travis.yml

@@ -21,4 +21,5 @@ addons:
     - gcc-arm-none-eabi
     - binutils-arm-none-eabi
     - libnewlib-arm-none-eabi
+    - diffutils
 after_success: bash util/travis_compiled_push.sh

util/install_dependencies.sh

@@ -20,7 +20,8 @@ if [[ -n "$(type -P pacman )" ]]; then
     arm-none-eabi-gcc \
     arm-none-eabi-binutils \
     arm-none-eabi-newlib \
-    git
+    git \
+    diffutils
 
 elif [[ -n "$(type -P apt-get)" ]]; then
   # Debian and derivatives
@@ -47,7 +48,8 @@ elif [[ -n "$(type -P apt-get)" ]]; then
     gcc-arm-none-eabi \
     binutils-arm-none-eabi \
     libnewlib-arm-none-eabi \
-    git
+    git \
+    diffutils
 
 elif [[ -n "$(type -P yum)" ]]; then
   # Fedora, CentOS or RHEL and derivatives
@@ -69,7 +71,8 @@ elif [[ -n "$(type -P yum)" ]]; then
     gcc-arm-none-eabi \
     binutils-arm-none-eabi \
     libnewlib-arm-none-eabi \
-    git
+    git \
+    diffutils
   # The listed eabi pacackes do unfortunately not exist for CentOS,
   # But at least in Fedora they do, so try to install them anyway
   # TODO: Build them from sources, if the installation fails
@@ -85,7 +88,8 @@ elif [[ -n "$(type -P zypper)" ]]; then
     patch \
     wget \
     dfu-programmer \
-    git
+    git \
+    diffutils
   # TODO: The avr and eabi tools are not available as default packages, so we need 
   # another way to install them