change ddf version to 1.1
update version
fix predict method in R
Merge pull request #48 from ljzzju/fixPredict

fix predict method in R
add avg function
add test for avg function
Merge branch 'ddf-sparksql-adatao' of github.com:ddf-project/DDF into ddf-sparksql-adatao
Merge branch 'master' into ddf-sparksql-adatao