Update MS SQL Server image to new official location (#992)

Fixes #944

Author: chungngoops

modules/jdbc-test/src/test/resources/container-license-acceptance.txt

@@ -1 +1 @@
-microsoft/mssql-server-linux:2017-CU6
+mcr.microsoft.com/mssql/server:2017-CU12

modules/mssqlserver/README.md

@@ -19,7 +19,7 @@ public class SomeTest {
         ... create a connection and run test as normal
 ```
 
-> *Note:* Due to licencing restrictions you are required to accept an EULA for this container image. To indicate that you accept the MS SQL Server image EULA, Please place a file at the root of the classpath named `container-license-acceptance.txt`, e.g. at `src/test/resources/container-license-acceptance.txt`. This file should contain the line: `microsoft/mssql-server-linux:latest`
+> *Note:* Due to licencing restrictions you are required to accept an EULA for this container image. To indicate that you accept the MS SQL Server image EULA, Please place a file at the root of the classpath named `container-license-acceptance.txt`, e.g. at `src/test/resources/container-license-acceptance.txt`. This file should contain the line: `mcr.microsoft.com/mssql/server:latest`
 
 ## Dependency information
 

modules/mssqlserver/src/main/java/org/testcontainers/containers/MSSQLServerContainer.java

@@ -7,8 +7,8 @@
  */
 public class MSSQLServerContainer<SELF extends MSSQLServerContainer<SELF>> extends JdbcDatabaseContainer<SELF> {
     public static final String NAME = "mssqlserver";
-    public static final String IMAGE = "microsoft/mssql-server-linux";
-    public static final String DEFAULT_TAG = "2017-CU6";
+    public static final String IMAGE = "mcr.microsoft.com/mssql/server";
+    public static final String DEFAULT_TAG = "2017-CU12";
 
     public static final Integer MS_SQL_SERVER_PORT = 1433;
     private String username = "SA";