Remove slashes from dimension names when creating dds responses (pydap server)

[Mikejmnez]

The following Pull Request:

• Closes pydap server returns broken DDS #496

This does not show up during testing, because it represents the case when reading data from an nc- file (as opposed to pydap dataset created for testing purposes)

Now the dds looks like:

Dataset {
    Float64 lon_bnds[lon = 180][bnds = 2];
    Float64 lat_bnds[lat = 170][bnds = 2];
    Float64 time_bnds[time = 24][bnds = 2];
    Float32 tos[time = 24][lat = 170][lon = 180];
    Float64 lon[lon = 180];
    Float64 lat[lat = 170];
    Float64 time[time = 24];
} tos_O1_2001-2002%2Enc%2Enc4;

and accessing using pydap now looks like:

open_url("http://127.0.0.1:8001/tos_O1_2001-2002.nc.nc4").tree()
.tos_O1_2001-2002.nc.nc4
├──lon_bnds
├──lat_bnds
├──time_bnds
├──tos
├──lon
├──lat
└──time

[Mikejmnez]

merging - pretty straightforward change