* add feign default http plugin
add test case for feign default http interceptor

* move feign and okhttp plugins to the parent moudle

Remove out-of-date readme file.

add okhttp plugin(provide synchronous http calls )

 Support leaf span

Remove "financial support", as I had already left OneAPM, and no financial relationship with OneAPM.

# Conflicts:
#	apm-sniffer/apm-agent-core/src/main/java/org/skywalking/apm/agent/core/conf/Config.java
#	apm-sniffer/apm-agent/pom.xml
#	apm-sniffer/apm-sdk-plugin/pom.xml

add test case for okhttp interceptor

* add plugins for resin-3.x and resin-4.x 

* Add mechanism to disable any or all plugins, Relate: #186

Support multi plugins for one target class

Rename the "apm-api" module to "apm-agent-core”. 

Update contributing guide.

fix functional issues after update new package name

2. Some class check style error.

chore(project): add the .gitignore file to project

Redis plugin cannot work on tomcat

Prepare for release 3.0.1

* feature/159:
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  Add log4j.xml into test package

modify the expose port of collector image