2 fixes: - mysql_write(): fix when connection is already available, required initial fetch():   - Pipelet.._add_input() takes proper care of everything including initial fetch()     this was already used for mysql_read() - mysql_configuration(): Add fork tag because this is a Multiton and   mysql_connections() is a singleton.
2 fixes:
- mysql_write(): fix when connection is already available, required initial fetch():
  - Pipelet.._add_input() takes proper care of everything including initial fetch()
    this was already used for mysql_read()
- mysql_configuration(): Add fork tag because this is a Multiton and
  mysql_connections() is a singleton.

ReactiveSets/toubkal_mysql,ReactiveSets/toubkal_mysql