remove useless code in boost_page_route

-  boost_page_route_test.dart
test `of` and `tryOf` method

- Remove overridden buildTransitions method because it seems useless.

- Also removed Stub, didn't find it used.

[sync] 2020/2/20

[sync] 2020/2/20

add travis url

# Conflicts:
#	android/build.gradle
#	android/src/main/java/com/idlefish/flutterboost/Platform.java
#	example/android/app/build.gradle
#	ios/Classes/Boost/FlutterBoostPlugin.h
#	ios/Classes/Engine/FLBFlutterEngine.m
#	lib/flutter_boost.dart

修正present问题并添加测试用例

2. fix present页面僵死问题
3. 增加present的测试用例

[Android] 在createEngine增加一个回调，方便在使用测做一些事情(打点之类)

[bugfix] fix crash：'FlutterBoostPlugin not register yet'

         // case: initFlutter after Activity.OnCreate method，and then called start/stop crash
         // In SplashActivity ,showDialog(in OnCreate method) to check permission, if authorized, then init sdk and jump homePage)
         // with this case, do initFlutter on SecondActivity.OnCreate

Update README.md / README_CN.md

Update Boost version desc.

[sync] 2020/1/19

修改Webview 多个页面来回切换的时候，在XTextInputPlugin的194行会报空指针异常

merge hotfix to add new api to allow client control whether flutter boost handle the registration of all plugins