Add user-defined category-label colors (#1402)

* Add user-defined category-label colors

Fixes https://github.com/chanzuckerberg/cellxgene/issues/1152

As described in https://github.com/chanzuckerberg/cellxgene/issues/1307

* Respond to feedback from @bkmartinjr in nodejs

* Respond to feedback from @bkmartinjr in python

* Add tests to the server module

* Autoformat python, run linter

* Make colors_get error handling specific

* Respond to feedback from @bkmartinjr

* Respond to feedback from @bkmartinjr

* Fix whitespace

* Fix python lint errrors

* Update documentation

* Add --disable-user-colors option to launch and cxgtool.py

* Fix python formatting

* Rename '--disable-user-colors' to '--disable-custom-colors'

server/common/app_config.py

@@ -78,6 +78,7 @@ class AppConfig(object):
             self.user_annotations__ontology__obo_location = dc["user_annotations"]["ontology"]["obo_location"]
 
             self.presentation__max_categories = dc["presentation"]["max_categories"]
+            self.presentation__custom_colors = dc["presentation"]["custom_colors"]
 
             self.embeddings__names = dc["embeddings"]["names"]
             self.embeddings__enable_reembedding = dc["embeddings"]["enable_reembedding"]
@@ -275,6 +276,7 @@ class AppConfig(object):
 
     def handle_presentation(self, context):
         self.__check_attr("presentation__max_categories", int)
+        self.__check_attr("presentation__custom_colors", bool)
 
     def handle_single_dataset(self, context):
         self.__check_attr("single_dataset__datapath", (str, type(None)))
@@ -517,6 +519,7 @@ class AppConfig(object):
             "annotations_cell_ontology_enabled": False,
             "annotations_cell_ontology_obopath": None,
             "annotations_cell_ontology_terms": None,
+            "custom_colors": self.presentation__custom_colors,
             "diffexp-may-be-slow": False,
             "about_legal_tos": self.server__about_legal_tos,
             "about_legal_privacy": self.server__about_legal_privacy,