Added the basic data types

Added:
- Basic datatype classes

Updated:

Fixed:
Added the splitter

Added:
- Splitter functionality

Updated:

Fixed:
Added basic scafolding of core

Added:
- Basic scafolding of core: DownloadManager, Merger, Validator
- Some utility classed (UrlUtils, Logging)

Updated:

Fixed:
Add DefaultMerger and test

Added:
- DefaultMerger implementation

Updated:

Fixed:
- Added default values to Download
- Changed constant names for file extension to make them self
documenting
- Replaced hard coded file extension with constants
Merge branch 'merger' into development
Added validator and checksum functionality.

Added:
- Validator functionality.
- Checksum functionality.

Updated:

Improved:
- Added documentation.

Fixed:
Merge branch 'validator' into development
Merge branch 'development'