Add Material Blue Grey theme

data/themes.yml

@@ -99,3 +99,4 @@
 - { colors: '#278F0D,#19780C,#070708,#FFFFFF,#19780C,#FFFFFF,#F7FF00,#FF8669', name: 'Mean Green' }
 - { colors: '#B51815,#A51815,#FFFFFF,#B51815,#FF1815,#FFD21F,#FFE21F,#FF5555', name: 'Kansas City Chiefs' }
 - { colors: '#181818,#202020,#99CB3F,#FFFFFF,#202020,#FFFFFF,#99CB3F,#F7124E', name: 'Drund' }
+- { colors: '#607D8B,#546E7A,#90A4AE,#FFFFFF,#455A64,#FFFFFF,#B2FF59,#EF5350', name: 'Material Blue Grey' }