* fix breaking bug in image tiddler attachment
* fix comments
* fix code format
* refactor processIncomingTiddler flow
* remove whitespaces after if statements
* refactor attachment_blob persistence flow
* refactor process tiddler to support different attachments
* add tests for attachment
* add more attachement test cases
* working on adding instanbul for test coverage report
* code coverage report generation
* remove unnecessary packages
* fix comments
