Refactoring: adjust packages.
Big refactor:
Change package structure
Change API definition
Refine code
Remove unused dirs.
Remove old unsed dist jar.
Update gitignore
Change extra param to  'extras'
Add registrationID push support;   clear some code.
Add feature - baseResult to return rate limiting params.
Refine code - can use msgResult / receivedsResult to get all response info by hand.
Add some comments.
Add javadoc
Merge branch 'master' into dev
Remove docs - apidocs
Update pom for apidocs site.
Upgrade readme doc.
Use gh-pages to present apidocs from github site plugin.
apns_production params can only be set by jpush client instance.
Update readme for releases.
Remove unused dist/ lib/ dirs.
Remove deps in .classpath for gson jar.
version should have  -SNAPSHOT