Queries : role base query restriction fixes added

See merge request !138

Fdb operation: keeping file pointer and infile index in memory

See merge request !139

1. Add: Required data on get asset in header.
2. Fix: Update and delete operations for normal bucket.

update: updating lazywrite interval
modification:removing unnecessary files 

Add: FDB related security options

See merge request !137

1. Fix: Error not returned on validation fail

1. Add: FDB related security options.

Dgraph Dalhelper

See merge request !135

Fix: Panic if role based activity not present.

See merge request !136

1. Fix: Panic if role based type not present.

Add: Asset FDB and merged bucket type

See merge request !133

1. Fix: Failed to get asset fro Asset type FDB.

1. Fix: Required Error type not set in case of delete operation

1. Fix: Error while updating data which is not present

1. Fix: Asset not saved to mixed bucket due to extra index field "name".
2: Fix: Failed to get saved asset due to missing "rowID" in index.

1. FIx: Error not handled on index update