libmutter15+: use hex colors when calling Cogl.Color.from_string ()

Author: garaevdi

compositor/Background/Background.vala

@@ -90,7 +90,7 @@ namespace GreeterCompositor {
 #endif
             if (color == null) {
 #if HAS_MUTTER47
-                color = Cogl.Color.from_string ("black");
+                color = Cogl.Color.from_string ("#000000");
 #else
                 color = Clutter.Color.from_string ("black");
 #endif
@@ -109,7 +109,7 @@ namespace GreeterCompositor {
 #endif
                 if (second_color == null) {
 #if HAS_MUTTER47
-                    second_color = Cogl.Color.from_string ("black");
+                    second_color = Cogl.Color.from_string ("#000000");
 #else
                     second_color = Clutter.Color.from_string ("black");
 #endif

compositor/Background/BackgroundContainer.vala

@@ -29,7 +29,7 @@ namespace GreeterCompositor {
 
         public void set_black_background (bool black) {
 #if HAS_MUTTER47
-            set_background_color (black ? Cogl.Color.from_string ("Black") : null);
+            set_background_color (black ? Cogl.Color.from_string ("#000000") : null);
 #else
             set_background_color (black ? Clutter.Color.from_string ("Black") : null);
 #endif

compositor/WindowManager.vala

@@ -99,7 +99,7 @@ namespace GreeterCompositor {
             stage = display.get_stage () as Clutter.Stage;
 #endif
 #if HAS_MUTTER47
-            stage.background_color = Cogl.Color.from_string ("black");
+            stage.background_color = Cogl.Color.from_string ("#000000");
 #else
             stage.background_color = Clutter.Color.from_rgba (0, 0, 0, 255);
 #endif
@@ -120,7 +120,7 @@ namespace GreeterCompositor {
                 width = width,
                 height = height,
 #if HAS_MUTTER47
-                background_color = Cogl.Color.from_string ("black")
+                background_color = Cogl.Color.from_string ("#000000")
 #else
                 background_color = Clutter.Color.from_rgba (0, 0, 0, 255),
 #endif