[debian] build the book with no auto-compression of book files (closes: #1906581)
Book content paths (html and rest) are now excluded from Debian compression step.
This will fix a documentation search issue on the website (doc.cubicweb.org)
Documentation build is now made optional since it can break for old distributions
and we don't want to block a new release of Cubicweb because of documentation issues.
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/common/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/entities/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/ext/ usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/ usr/share/cubicweb/
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/*.py usr/share/pyshared/cubicweb