Googletest not optional as tests are built by default

Author: suttonpd

README.md

@@ -27,8 +27,6 @@ Build Preparation
   * libsctp:             <https://github.com/sctp/lksctp-tools>
   * yaml-cpp:            <https://github.com/jbeder/yaml-cpp>
   * PolarSSL/mbedTLS:    <https://www.trustedfirmware.org/projects/mbed-tls/>
-
-* Optional:
   * googletest:          <https://github.com/google/googletest/>
 
 You can install the build tools and mandatory requirements for some example distributions with the commands below: