Give the ability to install googletest/simpleamqp to custom location

[bill-luu]

Some distros do not have /usr/local/lib or /usr/local/include in their source paths, or do not automatically include those directories.
We should modify googletest-setup.sh and rabbitmq-setup.sh to:

• By default, install to /usr/local/lib

• Allow setting of the installation paths via command line arguments:
  ./googletest-setup.sh -d /my/custom/dir

• Include a -h option to describe usages.