dovetail tool: Add an option cmd for pushing results into DB

dovetail tool: Add an option cmd for pushing results into DB

JIRA: DOVETAIL-373

1. add an option --report/-r to choose the report type.
2. "-r file" will store results with files.
3. "-r http://192.168.135.2:8000/api/v1" will push results into DB.
   The DB url can replaced by user's local DB or official DB.
4. Default report type is defined as "report_dest" in dovetail_config.yml.
5. Yardstick can't push results of one testcase into DB now, so both "-r file"
   and "-r http://..." will be regarded as "file".

Change-Id: Ieaa017ab59c5b15235bf306ef57cdc56beb22af8
Signed-off-by: xudan <xudan16@huawei.com>