Convert calibre modules to ebook_converter.

Here is the first batch of modules, which are needed for converting
several formats to LRF. Some of the logic has been change, more cleanups
will follow.

ebook_converter/main.py

@@ -0,0 +1,17 @@
+#!/usr/bin/env python
+import sys
+
+# TODO: remove this crap
+sys.resources_location = ''
+sys.extensions_location = '/usr/lib64/calibre/calibre/plugins'
+sys.executables_location = '/usr/bin'
+
+from ebook_converter.ebooks.conversion.cli import main
+
+
+def run():
+    sys.exit(main())
+
+
+if __name__ == '__main__':
+    run()