Fix build to allow custom boost, llvm and phasar directories.

[ddiepo-pjr]

The build was assuming that boost was installed to the default system
location and accessible, however for using this as a library I want to
use a custom installed boost to match the version of boost used by the
application. Most of the changes to CMakeLists are to use find_package
to locate the desired boost libraries. I believe this is the preferred
way to include boost libraries.

Also, this changed to allow llvm to be installed to a specified
directory. This change allows the developer to work with multiple
different versions for different projects.

The bootstrap.sh changes include:

• This also includes a change to specify the exact directory for phasar
  to be installed to. This allows the developer to have multiple
  installations.
• The git submodule init / update was required for a fresh install. I'm
  guessing this was just accidentally commented out.
• Removed the package libmysqlcppconn-dev which isn't necessary to
  copmile. Perhaps there's another dependency somewhere else, but I
  specifically removed this because it also pulls in a bunch of other
  dependencies (notably boost, and I specifically do not want the
  maintaner's version of boost installed).
• Added ability to specify the boost install dir to use.
• Added ability to run unit tests (I haven't verified this
  functionality, but it did work prior to the big merge last week).