Initial JetBrains support - Idea and PyCharm Community Editions.

Work in progress, do not merge yet.

DownloadCenter grew support for custom headers in DownloadItems.
Support for PyCharm and Idea Community Editions.

Need to add tests and refactor the JetBrains stuff a little so more logic is in the base JetBrains installer - this will allow us to add support for more IDEs easily.
no, there are two modes for the decompressor currently:
- don't provide any parameter and it will extract the whole tar/zip content to the destination directory
- or specify on directory and it will extract the content of that directoy into the destination.

I didn't see the value of merging multiple directories content from a tar into the destination, as I guess that most software will expect to have the parent dir in that case?

You can use for now dir_to_decompress_in_tarball='pycharm-community-*', the glob is supported in the decompressor (and is covered by tests)