Update uri dependency

ocaml-uri 1.3.13 introduced a sexp dependency to Uri, leading to compilation failure with an earlier ocaml-uri.
Re-run oasis setup.
Merge pull request #98 from j0sh/patch-1

Update uri dependency
test get_media_type
Merge pull request #99 from rgrinberg/master

test get_media_type
add strings module

The most common splitting in cohttp falls in two 2 categories:

- unbounded split on a single char
- bounded split on a single char

this module provides both functionalities through the split function
add tests for internal strings module
update _oasis

- mark Strings as internal module
- Add a test section for strings' tests
oasis regen
uses Strings.split where possible
remove module aliasing of Re_str

It was used for only a single function. Makes it harder to grep for
things
add the trivial strings_after function
add various little helpers to create specialized parsers

for headers, cookies
add cookie/header splitters
remove useless creation of re

this one was not being used
make cookie/header use specialized parsers
get_media_type now uses Re directly instead of Re_str

not the fastest but at least it's threadsafe (but very ugly)
add printer to media type test
lift Str.quote from ocaml-re

This commit might not be completely necessary but with it we still
need Re_str present. This way we can be 100% Re_str free.
rename Strings -> Stringext