1) import with updating index entries instead of replacing existing index file
2) atomic replace support for darwin platform

added feature to import/export as fdb data in zip format

1. Fix: got length of cyphertext is less than 0 error on empty file read.

1. Fix: Disable encryption for append bucket as no way to read encrypted data.

fix: exporting index files by filtering with queries 

1. Add: Lazy writer for append bucket

1. Add: Enable lazy writing for normal bucket

added feature to export and import data into fdb

Fix: Index file not created in some cases. Ex. For asset FDB on another drive.

removed unnecessary logs

1. Fix: Failed to get json data from pack on asset update.
2. Fix: Failed to get content-type from meta data.

1. Add: Hash length check to avoid runtime panic

1. Fix: Os specific row id generation.

1. FIx: Normal bucket operations

1. Fix: Decryption failed on read from normal bucket with security enabled. Fixed by passing compression flag to FDBSecParams.

Fix: invalid result in some operations. Changed rs.vlaue check to array length.

1. Fix: "No data found" error check failed. Check error message instead of value.

1. Add: FDB security for normal bucket

1. Fix: "please specify filetype" error on first save. Set Fieldquery only if it is provided.

1. Add: Lock for CRUD operations in pack bucket

1. Fix: "requiredData" not updated in index file

1. Fix: Failed update and upsert media operations due to row name conflict. Chnaged rowId from IndexNameQuery to relative filepath hash.

1. Add: Enable FDB security for Pack and Mixed Bucket

1. Refactor: Move FDBSecParams struct to securitymdl to make it accessible to filepack package. Will get cyclic dependency issue if kept in corefdb package.

1. Addressed unhandled errors, variable assignments.
2. Commented dead code. Can be removed after stable release.

1. Add: Security for Normal bucket files

1. Add: Shared file encryption for Normal bucket in FDB.

1. Add: Enable host wise compression for fdb

1. Add: Enable host wise security for fdb