build: replace fest with assertj

etl/build.gradle

 dependencies {
-  testCompile "org.easytesting:fest-assert-core:2.0M10"
   testCompile "com.google.guava:guava:16+"
 }

etl/src/test/java/EtlTest.java

 import java.util.List;
 import java.util.Map;
 
-import static org.fest.assertions.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThat;
 
 public class EtlTest {
     private final Etl etl = new Etl();

grade-school/build.gradle

-dependencies {
-  testCompile "org.easytesting:fest-assert-core:2.0M10"
-}

grade-school/src/test/java/SchoolTest.java

-import static org.fest.assertions.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThat;
 
 import org.junit.Test;
 

meetup/build.gradle

 dependencies {
   compile "joda-time:joda-time:2.3+"
-  testCompile "org.easytesting:fest-assert-core:2.0M10"
 }

meetup/src/test/java/MeetupTest.java

 import org.joda.time.DateTimeConstants;
 import org.junit.Test;
 
-import static org.fest.assertions.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.joda.time.DateTimeConstants.*;
 
 /*

nucleotide-count/build.gradle

-dependencies {
-  testCompile "org.easytesting:fest-assert-core:2.0M10"
-}

nucleotide-count/src/test/java/NucleotideTest.java

-import static org.fest.assertions.api.Assertions.assertThat;
-import static org.fest.assertions.api.Assertions.entry;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.entry;
 
 import org.junit.Test;