Updated CS identity from CS Systèmes d'Information to CS GROUP

src/site/markdown/contributing.md

src/site/markdown/design/design.md

src/site/markdown/design/digital-elevation-model.md

src/site/markdown/design/overview.md

src/site/markdown/design/technical-choices.md

src/site/markdown/downloads.md

src/site/markdown/faq.md

src/site/markdown/guidelines.md

src/site/markdown/index.md

src/site/markdown/sources.md

src/site/markdown/tutorials/direct-location-with-DEM.md

src/site/markdown/tutorials/direct-location.md

src/site/markdown/tutorials/inverse-location.md

src/site/markdown/tutorials/matlab-example.md

src/site/markdown/tutorials/tile-updater.md

src/site/site.xml

src/test/java/org/orekit/rugged/TestUtils.java

...a/org/orekit/rugged/adjustment/AdjustmentContextTest.java

...adjustment/InterSensorOptimizationProblemBuilderTest.java

src/test/java/org/orekit/rugged/api/RuggedBuilderTest.java