Handle process types names containing unsupported characters

[runesoerensen]

The CNB spec allows for process type identifiers containing alphanumeric characters and the characters ., _, and -.. This buildpack will currently try to add any detected project executables to the launch process list.

However, Heroku doesn't support process type names containing ., which is often used in .NET projects names, leading to errors when trying to deploy to Heroku. We could handle this scenario more gracefully in a few ways:

• When no Procfile is present, we may want to either remove . from the detected process type name, and/or print a warning with relevant instructions on how to mitigate the issue (e.g. by setting the AssemblyName project property, renaming the project file, or opting out of automatic process type registration).
• Skip process registration with Procfile #185 will allow users to opt out of this functionality altogether by adding a Procfile.