New files needed for creating the List Tree Table using Jquery Treetable

GCP-10444

Reviewer: Aldrin Batac
Included new css and js files for jQuery Treetable

GCP-10444

Reviewer: Aldrin Batac
Replace the included file of the html page used by Nursery and Trial Manager to display the germplasm list tree table

GCP-10444

Reviewer: Aldrin Batac
Implemented the services and javascript methods used in displaying the germplasm list tree table

GCP-10444

Reviewer: Aldrin Batac
Unit tests for displaying the germplasm list tree table

GCP-10444

Reviewer: Daniel Villafuerte
Use static import for Assert methods and Mockito methods

GCP-10444

Reviewer: Daniel Villafuerte
Code cleanup
1. Removed useless imports and unused variables
2. Used constants for repeated string literals
3. Used logger for error message
4. Moved literals on the left side of the equals comparison
5. Used isEmpty() instead of size()
6. Moved comments on top of code
7. Used interface instead of concrete classes for declarations
8. Threw a specific Exception subclass instead of Exception
9. Removed auto-generated TODO comments
10. Merged dangling if statements
11. Removed trailing whitespaces

GCP-10444

Reviewer: Daniel Villafuerte
Merge branch 'master' into branch_GCP-10444