build: fix make distcheck

when building with make distcheck, we are performing an out of tree
build with non standard prefix and non standard exec-prefix,
that will run the test suite and perform an install/deinstall test.
Everything needs to work based on those non standard paths and
DESTDIR is not defined / used.

• distribute all files required to build the source
• clean more temporary build files
• drop SOCKETDIR completely as it´s not used anywhere
• make ocfdir non-standard prefix-aware
• build test suite to deal with non-standard prefixes
• adjust man page generations to use builddir (untested with asciidoctor, not available in Fedora)
• fix some spacing here and there to make things look nicer (damn ocd)
• update .gitignore

Signed-off-by: Fabio M. Di Nitto <fdinitto@redhat.com>