KIJIMR-46. Update package-info for reducers package and removed duplicate AvroReducer

Signed-off-by: Christophe Taton <taton@wibidata.com>
KIJIMR-69. Remove unused TextInputDescriptorParser

Signed-off-by: Christophe Taton <taton@wibidata.com>
KIJIMR-72. Removed KijiTableImportDescriptor(its new home is in the Kiji MapReduce Library).

Signed-off-by: Christophe Taton <taton@wibidata.com>