modules: parsing manifest.yaml with minimal set of fields

[dmyger]

It's necessary to read a minimum set of fields from the manifest file.
Required fields:

• version - (Mandatory) specifies a string - as the version of this module itself.
• main - (Mandatory) Contains a string to start the main executable file of the module.
• help - (Mandatory) Field with the brief information on the command.
• tt-version - (Optional) specifies the minimum tt version the module is designed to work with.
• homepage_url - (Optional) Information about the module's repository or its homepage.