Nearest Neighbor solver, basic caching

Add a nearest neighbor solver (WriteAwareBruteSolver) and some basic
caching to the Java API adapter.

Fix a comment typo with an off-by-one error

src/test/java/com/cleverthis/interview/SolutionTestBase.java

@@ -21,6 +21,10 @@ public abstract class SolutionTestBase {
         assertTrue(padlock.isPasscodeCorrect());
     }
 
+    /**
+     * Tests padlocks with numpad sizes of 1 to 7. This test runs for every class that extends this SolutionTestBase
+     * abstract class.
+     */
     @Test
     void verify1to7() {
         for (int i = 1; i <= 7; i++) {