speed up local build time by 97% (#82)

* skip the exhaustive `generateBucketValueDistribution` when we're not
testing on Travis builds
* Check for ENV variable set to true by default by travis.
* use exhaustive test for gradles

Author: wangjoshuah

.travis.yml

@@ -6,6 +6,7 @@ jdk:
 install: true
 script:
     - "./gradlew clean"
+    - "./gradlew exhaustiveTest"
     - "if [[ -n $TRAVIS_TAG ]]; then
           ./gradlew ship;
       else

core-api/src/test/java/com/optimizely/ab/bucketing/BucketerTest.java

@@ -16,14 +16,16 @@
  */
 package com.optimizely.ab.bucketing;
 
+import ch.qos.logback.classic.Level;
 import com.optimizely.ab.bucketing.internal.MurmurHash3;
 import com.optimizely.ab.categories.ExhaustiveTest;
 import com.optimizely.ab.config.Experiment;
 import com.optimizely.ab.config.ProjectConfig;
 import com.optimizely.ab.config.TrafficAllocation;
 import com.optimizely.ab.config.Variation;
 import com.optimizely.ab.internal.LogbackVerifier;
-
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import org.junit.Assume;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.experimental.categories.Category;
@@ -36,9 +38,6 @@
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import ch.qos.logback.classic.Level;
-import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
-
 import static com.optimizely.ab.config.ProjectConfigTestUtils.validProjectConfigV2;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -79,6 +78,7 @@ public void generateBucketValueForNegativeHashCodes() throws Exception {
     @Test
     @Category(ExhaustiveTest.class)
     public void generateBucketValueDistribution() throws Exception {
+        Assume.assumeTrue(Boolean.valueOf(System.getenv("CI")));
         long lowerHalfCount = 0;
         long totalCount = 0;
         int outOfRangeCount = 0;