The only real purpose of strslice.StrSlice is to provide a custom
json.Unmarshaler implementation for API responses. For all other purposes,
it's a regular string-slice.
This patch removes uses of this type in cases where the custom json.Unmarshaler
is irrelevant; in most cases this was in tests, where results were tested
using "DeepEquals"; for those tests, the type-assertion did not add real
value, so we can cast the values to a []string instead.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>