add config for travis ci fail when test case fail

[lovepoem]

What is the purpose of the change

add config for travis ci fail when test case fail

Brief changelog

update .travis.yml

Verifying this change

When one unit test case fail, travis CI should get red (fail)

[codecov-io]

Codecov Report

Merging #1264 into master will decrease coverage by 0.14%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1264      +/-   ##
==========================================
- Coverage   32.29%   32.14%   -0.15%     
==========================================
  Files         691      691              
  Lines       34535    34535              
  Branches     6811     6811              
==========================================
- Hits        11154    11103      -51     
- Misses      21456    21503      +47     
- Partials     1925     1929       +4

Impacted Files	Coverage Δ
...om/alibaba/dubbo/rpc/filter/ActiveLimitFilter.java	77.77% <0%> (-11.12%)	⬇️
...ubbo/rpc/protocol/dubbo/ChannelWrappedInvoker.java	41.66% <0%> (-8.34%)	⬇️
...n/java/com/alibaba/dubbo/common/utils/JVMUtil.java	74.07% <0%> (-7.41%)	⬇️
...mon/serialize/support/dubbo/GenericDataOutput.java	68.42% <0%> (-7.02%)	⬇️
...a/dubbo/remoting/transport/netty/NettyChannel.java	61.25% <0%> (-5%)	⬇️
...mmon/serialize/support/dubbo/GenericDataInput.java	59.84% <0%> (-3.87%)	⬇️
.../dubbo/rpc/protocol/dubbo/filter/FutureFilter.java	54.54% <0%> (-2.03%)	⬇️
...dubbo/rpc/protocol/dubbo/CallbackServiceCodec.java	77.2% <0%> (-1.48%)	⬇️
...libaba/dubbo/rpc/protocol/dubbo/DubboProtocol.java	59.45% <0%> (-0.91%)	⬇️
...baba/dubbo/remoting/transport/mina/MinaClient.java	59.42% <0%> (+1.44%)	⬆️

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[lovepoem]

After the test , the new config is ok