Databases, Tables and Column info added

New

• Add schemas, tables and columns in information schema (#12) [Rajat
  Venkatesh]

  Information schema also processes PII in column parameters.

• Rescan permissions when GRANT/REVOKE succeeds. [Rajat Venkatesh]

• Support TableWithColumns grant type. [Rajat Venkatesh]

  The default permissions type is TableWithColumns for users even if no
  column permissions are set. Support the case where column wildcard is
  empty.
  Parse ARN of principals and only print the type and name.

Minor changes:

• Fix head line message in user.
• Add logs in scanner.
• Remove unused imports.

Fix

• Fix handling of syntax errors. Ensure app does not exist. [Rajat
  Venkatesh]

  Ensure SQL errors are handled correctly by importing operationalerror.
  Ensure grant/revoke syntax errors get the right message and are reported
  correctly.

  Fix #10