Add Media benchmark

Add package Benchmark/Media. The purpose of these models is to compare the performance of Annex60.Media.Water with Modelica.Media.Water.ConstantPropertyLiquidWater.

For a very simple case with a pump, a DynamicPipe and a boundary, the model with Water_a60 is about 3 times slower than with Water_cstProp:
![simplemodel](https://cloud.githubusercontent.com/assets/2987659/4057851/41567fca-2dce-11e4-894e-19691ec2b1b9.PNG)

For a more complex cases with two pipes in series and variable pipe temperatures, the model with Water_a60 is about 5 times slower than with Water_cstProp:
![complexmodel](https://cloud.githubusercontent.com/assets/2987659/4057864/6b19fb48-2dce-11e4-8b33-d89bae050e8f.PNG)

Finally, the model Annex60.Experimental.Benchmarks.Media.PumpWithPipeHeatPort_failToReduceDAEIndex2 illustrates that regardless of the media implementation, a DynamicPipe connected to a temperature boundary which changes on a discrete way leads to compilation failure.