Release of 1.5.6

- 4ec663e4fb63c4df5e77743b2031f389bf885f0c: Merge pull request #1368 from mattrjacobs/upgrade-jmh
- 082ac5b60328a6a026c7b0ce78479862651806db: Upgrade jmh to 1.14.1
- 02b8be7475acdb2913a1fee93bb753add753658f: Merge pull request #1365 from mattrjacobs/upgrade-nebula-and-gradle
- 14df0f4c1fac1f9f1e88ae20767a1e2bb69c2cc6: Upgrade to Gradle 3.1 / Nebula 3.4.0
- 9433411079378848ac822251fe7a5d877fa81386: Merge pull request #1364 from mattrjacobs/fix-backwards-incompatbility-for-appengine
- cdd4dc03b2c6b694362bb54cf001a6c8815b20ff: Merge pull request #1363 from mattrjacobs/fix-semaphore-only-groups-from-showing-up-in-threadpool-output
- ddbf1bbb5726792143bcbd5eee60df44e6ed7b57: Re-add PlatformSpecific.isAppEngine() for backwards-compatibility
- 04f33ad452a92cd4d42853a5f351bdd588a72ff0: Filter out all thread pool objects from thread pool metric streams which have not executed a command
- d31ec7d8e871bf35b473127d6112bc0cd31f0f99: Merge pull request #1360 from mattrjacobs/convert-command-construction-jmh-test-to-singleshot
- 62edc4a445b2a43777cda8217a277cec3fdee9d4: jmh test is more accurate when measuring the first command construction
- f16c08f5ba6e9a55535e4d67fd3663cf832d4d1e: Merge pull request #1356 from cadef/platformspecific_gae_flexible
- 023cd42eb2ef5a69d766c605e1a4376633ae8cfd: Update PlatformSpecific to only detect App Engine Standard Environment
- a0e233aeb3cbe2b218d24c82618c63cf7d38483b: Merge pull request #1353 from mattrjacobs/upgrade-rx-1-2
- eaec273bc48baa16da8accd9ec25a512f3d9973c: Upgrade to RxJava 1.2.0
- 8738d1c2a5a9abe839011fa5f500617aafb5781b: Merge pull request #1351 from mattrjacobs/remove-histogram-object-pool
- cc8f9737d34ea16da47e3b5ff5f41b04241724a3: REmoev object-pooling from CachedValuesHistogram
- d838f4d1ba65ce55755ab1c73f74c980f04572bf: Merge pull request #1336 from kennedyoliveira/feature/dashboard_improviments
- fe83e4957ca83b3a651016246f1c04408fe00ac5: Merge pull request #1320 from zsoltm/1.5.4.collapse-observable
- e9cf47bec1aba4c062085e93b547d721ebea9db4: added reactive collapser example
- 695ee06542c6dedbd1c700b497f3b1b5f50fdefe: review: removed unnecessary generics
- cbecc005a244a42f363e710d396c6c094ffcc206: review items: unnecessary checks; numeric constant instead of loop var
- b4d129e8cab3d2282d0bfd24836e45a28f9d43f4: Merge pull request #1341 from dmgcodevil/iss1328
- 13b4cde2a21a7e181e020ca8a0927033321cbcbc: iss1328: improved error messages
- c3a2282bb6630291ac6bc133034a21d8b590c791: iss1328: fix
- 12ad3e049f1bfa520cc39dd8a28806955fa0147d: Merge pull request #1340 from mattrjacobs/refactor-user-defined-fallback
- ce1caab677b33cac0cedc92c9ae5762f4d36a522: Made the user-defined fallback calculation more general
- 417b2490dba57e8ac19892c946f6eb3cc55f9e2e: Add remove button for streams
- 86760bdc9c7f977bbf9d64596ad0fa92afe69376: Improving dashboard eureka integration - Refactoring code - Grouping instances by services - Added a new group for the first instance of each server - Updating url on chaning stream type - Update title for with application name
- 5ca732a4ae90cc003c0fde16a4a1223555247724: Update CHANGELOG with v1.5.5
- 94ff54dce96913705d461833827563f2bd667cda: implemented basic Javanica collapsible Observer support
