RFC:   iRODS support with autoconf

An initial pass at adding configuration support for iRODS using autoconf. The intention
is that aside from running autoconf, all previous Makefile behaviour is preserved.

* The original Makefile becomes Makefile.in, preserving the custom
   build behaviour. The package version and SO version are configured
   in configure.ac.
    
* iRODS is off by default and enabled using --with-irods=/path/to/irods
  or just --with-irods where a default path is used.
    
* A -O option has been added to test_view and
   "test_view.pl irods" will run test_view.pl as normal, but writing
   its results directly into iRODS.
    
* The Travis config is updated to run configure.