[loader] remove deprecated phpcr loader
Merge pull request #292 from formapro-forks/data-loader-remove-deprecated-loader

[1.0][loader] remove deprecated phpcr loader
[tests] increase code coverage by tests.
Merge pull request #290 from formapro-forks/helere-tests

[1.0][tests] increase code coverage by tests.
[data loader] rework to return binary instance. add mime type guesser.