Update ncover custom tasks to take path to xunit

[petemounce]

xunit 1.5 introduces possibility of wanting to run the x86 runner vs the x64 runner. Should be possible to push in a preference when (for example) on an x64 box running a set of tests using the x86 runner (because the test DLL depends on something that is x86-only, like WatiN).

[petemounce]

Fixed in 0.2.0. NCover now has the possibility to take the command-line to run ncover-profiler against, which itself can be generated by the NUnit/XUnit command wrappers, or just passed as text.