Update Azure CI ubuntu from 16.04 to 18.04 due to 16.04 will be removed soon
Fixed some consistently failed tests
* fix TestCOWDataSourceStorage TestMORDataSourceStorage
* reset mocks
Also update readme badge
Co-authored-by: Raymond Xu <2701446+xushiyan@users.noreply.github.com>
* fix azure pipeline configs
* add pentaho.org in maven repositories
* Make sure file paths with scheme in TestParquetUtils
* add azure build status to README