add sort option on query
add example to sort query
support backward code compatibility; add test code
Merge pull request #104 from furushchev/add-sort-query

add sort option on query
Merge branch 'hydro-devel' of https://github.com/hawesie/mongodb_store into hydro-devel
Added test_mode flag to launch file.
Merge branch 'hydro-devel' of https://github.com/hawesie/mongodb_store into hydro-devel