Add ability to change icon
Add ability to change icon

Add ability to change defined social network icon in Core. Use array union instead of array merge.
With this change we can change social-icon from config file.
Example: facebook -> facebook-square.
haeflimi/concrete5,mainio/concrete5,biplobice/concrete5,hissy/concrete5,concrete5/concrete5,deek87/concrete5,deek87/concrete5,biplobice/concrete5,hissy/concrete5,triplei/concrete5-8,olsgreen/concrete5,mlocati/concrete5,biplobice/concrete5,hissy/concrete5,a3020/concrete5,mainio/concrete5,rikzuiderlicht/concrete5,a3020/concrete5,concrete5/concrete5,MrKarlDilkington/concrete5,deek87/concrete5,triplei/concrete5-8,jaromirdalecky/concrete5,olsgreen/concrete5,MrKarlDilkington/concrete5,jaromirdalecky/concrete5,mlocati/concrete5,jaromirdalecky/concrete5,jaromirdalecky/concrete5,hissy/concrete5,haeflimi/concrete5,rikzuiderlicht/concrete5,haeflimi/concrete5,mlocati/concrete5,mlocati/concrete5,MrKarlDilkington/concrete5,concrete5/concrete5,mainio/concrete5,haeflimi/concrete5,concrete5/concrete5,olsgreen/concrete5,rikzuiderlicht/concrete5,triplei/concrete5-8,biplobice/concrete5,deek87/concrete5