Add UI relations for logger management

[jkall]

From [email protected] on February 11, 2014 12:51:37

Relate the new table ”loggers” to the plugin GUI and specifically obs_points custom edit form. The presence of loggers or not should be asked from table loggers and in the future, column ”obs_points”.”wlogg_yn” will be removed. ->Must maintain backwards compatibility!

Original issue: http://code.google.com/p/midvatten-plugin-for-qgis/issues/detail?id=44