Increase max dims in netcdf

This is needed for ExodusII. It is turned off by default, as it seems the
netcdf developers know about this issue:

http://www.unidata.ucar.edu/support/help/MailArchives/netcdf/msg09258.html

But they didn't change it by default. Here is another reference about it (https://cubit.sandia.gov/public/13.2/help_manual/WebHelp/finite_element_model/export/exporting_exodus2_file.htm):

> Note that the 'stock' ncdump utility should work for most meshes; however, Sandia increases some of the dimensions in order to handle larger meshes (more element blocks, boundary conditions, variables). The dimensions we increase in netcdf.h are:
>
> NC_MAX_DIMS (max dimensions per file) from 100 to 65536
> NC_MAX_VARS (max variables per file) from 2000 to 524288


Use this new feature as:
```
packages:
  netcdf4:
    increase_max_dims: true
```