fix Config unit tests side effects on other tests (task #69)
use dm_store, and add 'dm' subdirectroy to dm_store location for pairtree location
use md_store in tests
fix storage init, add missing dm dir
create dm dir
create only dm_store, not sub dm directory, created by pairtree directly
use the new configuration key for projects job execution directory.
handle argpos not here in the ancestor paragraph.
add Statistic and ServiceUsageStatistic classes for the statistics API
Merge branch 'develop' of https://github.com/mobyle2/mobyle2.lib into develop
Merge branch 'feature_command_builder' into develop
fix problem with argpos ordering in Mobyle service (task #71).
add unit tests for bug in task #71