Rename database client classes

Update our class names to reflect the new file structure introduced in
b700c1bef89a67a64f1040fb6bb03c0320eefe91.

Use the

    module DBShell
      module Client
      end
    end

syntax intead of `DBShell::Client` so that we don't have to define the
`Client` module in a separate file and require it. Otherwise we'd get an
error:

    lib/dbshell/client/sqlite3.rb:1:in `<top (required)>': uninitialized constant DBShell::Client (NameError)

0 files changed, 0 insertions, 0 deletions