Add CMake to requirements

Author: rpep

bin/install-ubuntu-packages.sh

@@ -1,4 +1,4 @@
 # required to compile fidimag
-apt-get install python-pip python-numpy python-dev python-scipy
+apt-get install python-pip python-numpy python-dev python-scipy cmake
 # required for tests and running it
 apt-get install python-pytest python-pyvtk ipython python-matplotlib