Clean up project content

Remove class payable and invoice, also payable interface test.
Modify existing class to suit needs and rename it better.
Working dashboard input and output

Optimize panel layout for more components.
Rename particular components with suitable name.
Put some labels before each text field.
Warn user in output if important input is missing.
Refine application logic

Add piece worker employee type.
Prepare for additional input by particular type

Fix some decimal format.
Change commission rate to percent.
Prepare to display inputted data.
Another project content clean up

Put name on header comment.
Flip default earnings and related logic
Create getEarnings and prepare for more input

Prepare for more additional employee information.
Create manifest file and prepare for jar file.
Specific foolproof and warnings.
Change some variable names.
Merge branch 'feature/dashInput' into develop