treat SHOW SLAVE STATUS as binary strings
decode string values from show slave status, ignoring decode errors

- fixed lp#1220841 where mysql fails to handle the encoding of
  some error messages correctly and show slave status fails.
  Here we perform a best-effort decoding and just strip out
  invalid characters from the output.  This should only affect
  the last_error field.
always raise BackupError rather than OSError

- this forces PgError to derive from BackupError so
  if this is raised we don't end up with an unchecked
  exception
- Also, when running subprocess.call catch OSError
  This means execve failed in some way - either the command
  was not found in PATH or there was some other related error
  in executing the command.
ensure pgdump control connections run in autocommit mode

- holland-pgdump runs some basic queries for database
  discovery and basic size estimation.  These should not
  hold an open transaction, however, so this fix
  ensure the connection is set to autocommit mode.
ensure holland-pgdump control connection is closed

- previously holland-pgdump had a bug that would leave
  active connections open while running pg_dump.  This
  fix more aggressively closes these connections to
  avoid leaving a dangling connection open. Specifically
  this closes the connection as soon as the backup started
  once we know estimation is over.
Merge branch 'feature/lp_1207852_improve_invalid_view_detection' into feature/lp_1262352_view_metadata
simplify transactional engine checking
ensure we compare engine names in lowercase
also treat views as transactional
Organizational Changes for Improving Provider Docs
Fixed provider reference, renamed config page

Fixed a provider reference located in config-backupsets. That list
is redundant and may be removed in the future, but regardless, the
path was wrong.

Also renamed config title from "Holland Configs" to "Configuring Holland"
CSS Fixes for Highlighting, TOC changes
Added gpg as a compression target
Added gpg support
options added to gpg command line
Added gpg option for mysqldump and xtrabackup
Replace defaults in xtrabackup provider to use innobackupex

- Upstream xtrabackup has deprecated innobackupex-1.5.1 and
  the holland defaults have become stale
- rename CHANGES.txt to CHANGES.rst and add missing entry for
  feature/innobackup151_deprecated
always pass sequences of parameters to cursor.execute

Fixes #106

Previously some queries were passing bare strings to
cursor.execute(query, param). This worked under MySQLdb 1.2.3
but fails under MySQL 1.2.5.  This is likely broken on other
connectors which also expect a sequence of params.
update CHANGES.rst for github issue #106

Notes fix for mysql-python compatibility in changelog.