Moved ELF related stuff to separate namespace.

Since we want to introduce support for the uImage, we have put ELF stuff in a non-root directory.
UImage class stub.
API changed to be similar to ELF's.
Modified Tests namespace in a similar manner to ELF's.
But of course Utilities should stay where they were.
First tests for UImages, bug fixes, more code.
Some properties of header added.

With tests.
Added timestamp and test for it.
The main course: extracting image.
Introduced image type which is also now checked.
Added header checksum calculation.
Added a test for the checksum calculation.
ImageType can now be read (+ test).
Image extraction improved.
Compression type should actually be read.
Added operating system.
Added architecture.
Test for #19.
Closes #19.
Merge branch 'uimage'

Conflicts:
	ELFSharp/ELF/IELF.cs
	Tests/Tests.csproj