Default labels should enable all road labels early

[nvkelso]

To match the JS rig, and related to tangrams/tangram#484 (comment). The older logic is from Tangram era 0.7 but articulated labels changes more recently and the about to land curved labels make these labels look good earlier now.

Here's what the JS has, the YAML for the default labels scene file should mark them true (currently false).

text_visible_highway_e = _default;
text_visible_minor_road_e = _default;
text_visible_highway_e = _default;
text_visible_trunk_primary_e2 = _default;
text_visible_trunk_primary_e = _default;
text_visible_secondary_e = _default;
text_visible_tertiary_e = _default;
text_visible_minor_road_e = _default;
text_visible_exits_e = _default;