Resolve "Change formula column type to text"

Closes #114 (closed)

src/main/java/nl/tudelft/submit/model/grading/GradingFormula.java

@@ -20,6 +20,7 @@ package nl.tudelft.submit.model.grading;
 import java.io.Serializable;
 
 import javax.persistence.EmbeddedId;
+import javax.persistence.Lob;
 import javax.persistence.MappedSuperclass;
 import javax.validation.constraints.NotBlank;
 import javax.validation.constraints.NotNull;
@@ -44,6 +45,7 @@ public abstract class GradingFormula<E extends Serializable> {
 	private E entityId;
 
 	@NotBlank
+	@Lob
 	private String formula;
 
 	@NotNull