ignore maven target files; add aquilon primer; provide skeleton for man page inclusion

The update to the .gitignore file ignores emacs backup files (for my sanity) and ignores the generated maven output files in the `target` subdirectory. 

The draft aquilon book now contains the 'Aquilon Primer' contents provided by Nick.  The overall text and skeleton will need further work, but this is a good start on the introduction.

The last commit shows the changes that will be necessary to integrate the man pages with the aquilon book.  These are minor: remove docbook declaration at the start and include the dobook namespaces on the first XML element.  I can make these changes; however, I don't want to have two sets of man pages in parallel.  So the question is:

Does MS want to continue to use the `make` build of the man pages?

* If not, it is straightforward to convert everything to the new version. 
* If so, can MS verify that that namespace/declaration change doesn't break the build via `make`?