Added some books

Removed some paid books and repetitions

- Removed 'E-Books Directory' because it's another list;
- Removed 'Messaging as a Programming Model' because it is not free;
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Book not freely available online.  Link points to a table of contents, not the actual contents of the book.

Mature Optimization is a free ebook that was an internal performance handbook for facebook.

Added two links under the hood of Microsoft technologies. The link contains lots of free ebooks by MSDN member Eric Ligman over a variety of topics such as Windows Azure, Windoes Phone Development, SQL Server, Windows 8 app development, Visual Studio Guides, SharePoint, etc

- ASP.NET MVC book is represents a deprecated version of ASP.NET MVC;
- Added JavaScript Garden tutorial;

Another Erlang programming book that isn't free!

Erlang programming book is not free!

added content for MATLAB programming

Salesforce developers actually have a great resource on Developer Force - http://developer.force.com/ - but I wanted to add some of the books Salesforce has released to this list to share with everyone. Salesforce's languages are Apex (similar to Java) and Visualforce (similar to HTML)

Added some books for Erlang