fixed build by removing inexistent class

Author: jaebradley

src/test/java/problems/impl/FirstMissingPositiveIntegerIdentifierImplTest.java

@@ -2,7 +2,6 @@
 
 import org.junit.Assert;
 import org.junit.Test;
-import problems.exceptions.NoFirstMissingPositiveIntegerException;
 import problems.interfaces.FirstMissingPositiveIntegerIdentifier;
 
 import java.util.Arrays;