add new base plugin directories

This creates the location to merge the current plugin schema
into holland-mysql, holland-lvm, holland-mysql-lvm and holland-pgsql
plugins.
add plugin package structure

This adds the holland.<plugin> namespaces:
holland.mysql
holland.lvm
holland.mysql.lvm
holland.pgsql
merge holland.backup.mysqldump into mysql namespace

- move holland/backup/mysqldump to holland/mysql/mysqldump
- remove old (unused) holland/lib/mysqldump code
- move tests from holland.backup.mysqldump under mysql
- move license files to mysql
add mysqldump backup plugin entrypoint
merge holland.lib.mysql into mysql plugin

- holland.lib.mysql.<module> renamed to holland.mysql.<module>
merge holland.backup.delphin into mysql package

- move holland/backup/delphini to holland/mysql/delphini
- rename holland.backup.delphini to holland.mysql.delphini
- move delphini tests to mysql/tests/delphini
- move delphini docs to mysql/docs/delphini
- add backup entrypoint for delphini plugin
merge holland.backup.pgdump into pgsql namespace

- rename pgdump tests to pgsql/tests/
- rename holland.backup.pgdump to holland.pgsql.pgdump
- move license files under pgsql
- add backup entrypoint for pgdump plugin
merge holland.backup.xtrabackup into mysql namespace

- move xtrabackup tests to mysql/tests/xtrabackup/
- rename holland.backup.xtrabackup to holland.mysql.xtrabackup
- add backup entrypoint for xtrabackup to mysql/setup.py
add holland.core.util.path:which

- simple python-which implementation to resolve a name
  to an absolute path from a command in PATH
remove plugins/holland.lib.common

- all functionality has been moved under holland/core
  * compression -> holland.core.stream
  * which -> holland.core.util.path:which
  * hooks -> holland.core.backup.hooks
  * archive -> unused functionality
remove sqlite and random backup plugins

These plugins had not been used for some time and were
just examples.  We have some example plugins in
holland/core that will provide a better starting point
merge script plugin with holland-core

- move script plugin to holland/core/backup/impl/script
- add entrypoint for script backup plugin to holland-core
- remove plugins/holland.backup.script
remove old ACTIVE file
merge holland.lib.lvm into lvm

- renamed holland.lib.lvm to holland.lvm
- moved holland.lib.lvm tests to lvm/tests
- moved README, LICENSE from holland.lib.lvm to lvm
- removed plugins/holland.lib.lvm
merge holland.backup.mysql_lvm into mysql-lvm namespace

- renamed holland.backup.mysql_lvm tests to mysql-lvm/tests
- moved licenses and readme to mysql-lvm
- renamed holland.backup.mysql_lvm package to holland.mysql.lvm
- added mysql-lvm, mysqldump-lvm, mylvmdump backup entrypoints
- removed holland.backup.mysql_lvm directory
adding missing [holland.backup] section to setup.py entrypoints
update package names in plugins

- renamed from holland-{name} to holland.{name}
  e.g. holland-mysql-lvm -> holland.mysql.lvm
exclude tests from packages
update holland.spec to reflect plugin reorg

- holland-{mysqldump,xtrabackup,common} -> holland-mysql
- holland-pgdump -> holland-pgsql
- holland-mysqllvm -> holland-lvm, holland-mysql-lvm
- start deprecating /etc/holland/providers/
- Obsolete old package names per Fedora Packaging Guidelines
cleanup old holland.lib.mysql references