Analyze and fix for use of StringBuilder.

The Analyzer will alert when have more than two concatenation in initialization
Test: (in) var teste = "A" + "B" + "C"; (out) var teste = new StringBuilder().Append("A").Append("B").Append("C").ToString();

To implement was need to create the files: UseStringBuilderToConcatenationAnalyzer.cs, UseStringBuilderToConcatenationCodeFixProvider.cs and the file of test UseStringBuilderToConcatenationTests.cs than contains the cases