change graph version to 0.28.4-public. and fix build break by specify… … javadoc plugin version

update version to 0.27.2-public 

shade pb in odps-sdk-core and odps-sdk-mapred 

update to 0.26.6-public 

update readmin 

update readme 

remove unnecessary files 

update github api key for travis 

add deploy config in pom.xml Change-Id: I686f1f7693b2f63f795e667fbded38ba99143f5a