[ISSUE #152] [UML_VIEW] Allow specifying java location

[svlad-90]

[ISSUE #152] [UML_VIEW] Allow specifying java location

1. [x] Have you followed the guidelines in our Contributing document?
2. [x] Have you checked to ensure there aren't other open Pull Requests for the same update/change?
3. [x] Have you built the project, and performed manual testing of your functionality for all supported platforms - Linux and Windows?
4. [x] Is your change backward-compatible with the previous version of the plugin?

Change description:

• Addition of the possibility to specify the java location in "UML_VIEW" via the different ways ( custom path, env. var, etc. )
• Extension of README to cover the new functionality

Verification criteria:

• Checked manually on the Windows 10 OS
• All sanity checks on the Git Hub were passed successfully