[Compatibility] Treat KIND values case-insensitive

There are clients/servers which set KIND:GROUP instead of KIND:group although RFC 6350 specifies "group" (lower-case) and values are case-sensitive.

For better compatibility, I suggest to make the equals() calls in Kind.is… case-insensitive:

ez-vcard/src/main/java/ezvcard/property/Kind.java

Lines 114 to 116 in b8f0a18

    
           public boolean isGroup() { 
        
           	return GROUP.equals(value); 
        
           }

Fixed in acbeb66.

ez-vcard version 0.12.1 has been released, which includes this bug fix!