khoros: support optional module and package configuration keywords
Add support in khoros configuration plugin for optional keywords module and package.
This enables:
- support for different python file name and class name
- support multiple classes in one module
- support for external packages
Example:
minimalistic: # class name == module_name; package = bliss.controllers.module_name
plugin: khoros
name: sr_current_v1
class: tango_fe
uri: orion:10000/fe/id/00
attr_name: sr_current
module: # package = bliss.controllers.module_name
plugin: khoros
name: sr_current_v3
module: tango_fe
class: tango_fe
uri: orion:10000/fe/id/00
attr_name: sr_current
package: # could put any class from any package
plugin: khoros
name: sr_current_v3
package: bliss.controllers.tango_fe
class: tango_fe
uri: orion:10000/fe/id/00
attr_name: sr_current
if package is given, module is ignored if present.