Added POST /tools/{id}/versions method

Description

Implemented the POST /tools/{id}/versions endpoint.
Now the POST /tools endpoint uses the former for adding/updating version information for a given tool, hence the code redundancy does not occur.
Support for additional ToolVersion attributes has been added. Fixes #33 Also Fixes #43
Type of change
[x] New feature (non-breaking change which adds functionality)

[x] My code follows the style guidelines of this project
[x] I have performed a self-review of my own code
[x] I have commented my code, particularly in hard-to-understand areas
[x] My changes generate no new warnings
[x] I have added tests that prove my fix is effective or that my feature works
[x] New and existing unit tests pass locally with my changes
[x] I have not reduced the existing code coverage
[x] I have added docstrings following the Python style guidelines of this project to all new modules, classes, methods and functions are documented with docstrings following; I have updated any previously existing docstrings, if applicable

[ ] Update the replace_one flow for file storage. Current implementation not working ideally when PUT /tools/{id} tries to update the file data corresponding a versions.