Edited Issue: MaxMemorySize on Linux; issue if not default [137]

Conditions

```
cd ~/src/codeplex/rdotnet/TestApps/MeasureRuntime/bin/Debug
./MeasureRuntime.exe
```
works, however
```
./MeasureRuntime.exe 1000 24 ~/tmp/rdotnetruntimes.csv
```
does not. Gets the followins crash

```
*** Error in `/usr/bin/cli': double free or corruption (fasttop): 0x00000000028e6b40 ***
Stacktrace:
```

The init of the R engine fails because of the following being added to the command line argument
```
argv.Add("--max-mem-size=" + parameter.MaxMemorySize);
```