Perform final migration of DAS python server to DAS go server

[vkuznet]

To finalize DAS migration from python to Go server a few tools should be taken care of:

• das_js_fetch to fetch das maps from given URL (bash script)
• das_js_validate to validate DAS Maps (bash scrip which calls $DASROOT/tools/schema_validators/validate_inputvals.py and validate_dasmaps.py)
• pymongostat to see Mongo statistics (python script pymongostat.py)
• das_js_import to import DAS maps into MongoDB (shell script call mongoimport which is Go tool)
• das_cleanup to remove old records from DAS cache (python script das_cleanup.py)
• das_dbs_update to update DBS records in DAS cache (possibly obsolete with dasgo server since we don't do autocompletion anymore); it is python script das_dbs_update.py
• das_create_json_maps python script to create DAS maps from DAS yaml files

Next, I'll need to clean-up das.spec to remove python dependencies and DAS python server.

[vkuznet]

New code is in: https://github.com/vkuznet/DASTools

[vkuznet]

• das_js_fetch [DONE]
• das_js_import [DONE]
• mongostatus.go replaced pymongostat [DONE]
• das_cleanup.go [DONE]

[vkuznet]

All scripts are implemented.