Organised imports.

Removed wildcards imports and explicitly imported required classes.
Removed space under method annotation

To keep annotation naming consistent with others annotations.
Added DBConnection singleton class

This class represents a single DB connection.
Reduced code duplication by using DBConnection object.
Added error code to stderr for DBConnection object.
Fixed annotation typo.
adbc h2 connection string is handled by DBConnection class
jdbc h2 connection string is handled by DBConnection class
Merge branch 'master' of https://github.com/RobertNorthard/environment-dashboard
Resolved merge conflict
Merge conflict resolved.
Moved DBConnection class to utils package.
Merge pull request #10 from RobertNorthard/master

Moved DBConnetion to utils package from model package.