Added support for Parastation MPICH toolchains with Intel compilers

Simple support for Parastation MPICH with intel compilers
maybe add a comment here why you're overriding what is being set by `IntelMKL`?

is this a fix specific to Parastation?

also: you're including the 'generic' `MPICH` component here, yet naming the toolchain specifically for Parastation.

Maybe here we should be using:

```python
class Impmkl(IntelIccIfort, Mpich, IntelMKL, IntelFFTW):
    NAME = 'impmkl'
    BLACS_LIB = [...]
```

and then on your end:

```class IntelPara(Impmkl):
   NAME = 'intel-para'
```

I'm OK with including the 'empty' `intel-para` toolchain definition in the framework as well if that makes things easier for you