Set date of thesis submission

Set the date on the title page according to the specifications of the
University of Cambridge.

thesis.tex

@@ -26,6 +26,7 @@
 \title{Investigating the link between\\tRNA and mRNA abundance\\in mammals}
 \subject{This dissertation is submitted for the degree of Doctor of Philosophy}
 \author{Konrad \second{Ludwig Moritz} Rudolph}
+\date{May 2015}
 \publishers{%
     %\vfill doesn’t work properly on title page due to excess glue
     \vspace{6\baselineskip}