Add ability to customize ssl mode settings PyMySQL#474(fixed comparas…

…ion and case sensitivity)

MySQLdb/_mysql.c

@@ -491,10 +491,10 @@ _mysql_ConnectionObject_Initialize(
 
     #ifdef MARIADB_BASE_VERSION
     if (ssl_mode) {
-        if (strcmp(ssl_mode, "PREFERRED") != 0)
+        if (strcasecmp(ssl_mode, "PREFERRED") != 0)
         {
             int enforce_tls= 0;
-            if (strcmp(ssl_mode, "REQUIRED") == 0)
+            if (strcasecmp(ssl_mode, "REQUIRED") == 0)
                 enforce_tls = 1;
             #ifdef MYSQL_OPT_SSL_ENFORCE
             mysql_optionsv(&(self->connection), MYSQL_OPT_SSL_ENFORCE, (void *)&enforce_tls);
@@ -540,7 +540,7 @@ _mysql_ConnectionObject_Initialize(
 #ifdef HAVE_ENUM_MYSQL_OPT_SSL_MODE
     if (ssl_mode) {
         char *corrected_ssl_mode = NULL;
-        if (strcmp(ssl_mode, "REQUIRED") == 0 || strcmp(ssl_mode, "VERIFY_CA"))
+        if (strcasecmp(ssl_mode, "REQUIRED") == 0 || strcasecmp(ssl_mode, "VERIFY_CA") == 0)
             corrected_ssl_mode = "VERIFY_IDENTITY";
         else
             corrected_ssl_mode = ssl_mode;