test cases for quadratics

Added some C test cases for the following problems:
```
minimize norm(x)
    x >= 0
```
```
minimize quad_over_lin(x,1)
  x >= 0
```
```
minimize square(norm(x))
  x >= 0
```
```
minimize sum(square(x))
  x >= 0
```

I chose this problem because it's a harder one for interior-point methods (I forget the reference, unfortunately, likely from Lieven?). If the constraint is removed, the problem is solved in 5 or so steps for ECOS. Interestingly, ECOS fails on the norm version.

I compiled these to C with QCML and call them in the `quadratics.h` header.