Adds a class to parse Sonar results.

SonarResultParser parses json result and produces a ReviewResult.

Change-Id: I11e2fc20567570343b20648f8d7ae8bc04d5940b
Adds a SonarProcessor class.

Change-Id: I86633f86858efbe9aaea177d68492c1ff937273e
Test that sonar parser only reports new issues

Add test fixtures that test sonar will only report new issues

Change-Id: I47dd6d4c088620bd5120a07a155e75ba0687b808
Use file basename instead of fullname in sonar

Some sonar plugin do no include git path as the source file path (for
example, sonar-visual-studio plugin generates filenames that are
relative to the module csproj file).

Using the file basename and a recursive match allows Sonar to match
modified files with their indexed names in Sonar.

Although this can generate useless analysis (as some files that are not
included in a review may be analysed), this has a limited additional
cost considering that few files have the same basename inside a
repository.

Change-Id: Ib74289e201098d15c618791f47b2dd657c3a1744
Update README

Add sonar as a tool for sputnik in the readme title

Change-Id: I53df772174a7b0478a992dc8a45c1cf844c8958b
Rename sonar configuration file key

As this configuration directive holds multiple configuration file paths
it has been renamed configurationFiles.

Change-Id: I33c4e37a8ac25a81868086a9bdd7d2c62685d517
Use TestEnvironment class and fix naming

Rename test and use TestEnvironment class as a base class for test
in order to use helper methods.

Change-Id: I413e2b5d536201dc59059b1fdc0a0c2c1073cc67