Add styles for <kbd> tag.

Adapt similar styling to Wikipedia.

Fixes #424
Fix handling of anchor links in guides print version.
Implement --exclude option.

Allowing to exclude some of the input files.
Comes in handy for Windows users especially.

Fixes #216
Updated Rally AppSDK link

I work for Rally Software and noticed the link was outdated. I've updated the link to a non-redirect link and updated to the latest App SDK release.
Merge pull request #426 from NicholasBoll/patch-2

Updated Rally AppSDK link
Use the new JSDuck logo in README.
Improve README.md.

Fix old links and simplify the Usage section - pointing people to
the new Usage guide in wiki for more.
Add Window and XMLHttpRequest to external classes list.

These come up fairly often. Better to have these built in.
Up version to 5.1.0.
Strip UTF-8 BOM when running under Ruby 1.8.

Fixes #427
Hide "Fires" section when empty :fires array.

When ever a method-call is detected inside a method, this results
in :fires field being created with possibly zero elements in it -
but the #to_html of Tag::Fires didn't account for it.

Fixes #428
Cosmetic margin fix for categories page

When the browser is narrow the floated columns all align left but with different margins. They should all have the same left margin so it looks consistent at any width.
Merge pull request #433 from bmoeskau/patch-1

Cosmetic margin fix for categories page
Remove the left margins of categories columns.

An improvement over the previous fix by Brian Moeskau.
Saving on the horizontal space by removing the left margings
altogether.
Only apply the UTF-8 BOM stripping in Ruby 1.8.

Something goes wrong when we execute this BOM-stripping code in
Ruby 1.8 which has encodings support.  Didn't care to digg into this,
and so I'm just limiting this fix to Ruby 1.8 where it's actually
needed.
Display "Nothing new" when no new items in this version.

Fixes #429
Generate docs for auto-generated setter parameter.

To avoid the no_doc_param warning.

Fixes #435
Remove extra dot from warning types docs.
Add tests for JsDuck::Logger.

Make the Logger testable by defining a LoggerCls and instantiating
it as global Logger - allowing us to instantiate the LoggerCls
separately in tests.

Test the enabling/disabling of warnings.
Extract Warnings class from Logger.

Test the warnings system through the Warnings class instead.
Switch Logger class back to the old system of including Util::Singleton.