Import needed parts from Industria

* oauth/utils/base64.scm:
* oauth/utils/sha-1.scm: New files, imported from Göran Weinholt's
  Industria library.

* configure.ac:
* oauth/Makefile.am:
* oauth/oauth1/signature.scm:
* oauth/utils/Makefile.am: Wire new files into build.

* README.org: No more dependency on Industria.
encode-and-sort-params doesn't mutate its argument

* oauth/oauth1/utils.scm (encode-and-sort-params): Use an explicit loop
  instead of assq-remove!, which may mutate its argument.
Fix requests with non-oauth parameters

* oauth/oauth1/utils.scm (oauth1-param?): New helper.
* oauth/oauth1/request.scm (oauth1-request-http-headers): Only put OAuth
  params in the Authorization header.
  (oauth1-request-http-url): By default, don't include OAuth params.
  (oauth1-http-request): Use oauth1-request-http-url, so we get the
  non-oauth params in the URL.

* oauth/oauth1/client.scm (oauth1-client-authorize-url): Include all
  params.