Integration tests emit Erlang noise on Windows

[cmbrandenburg]

The cargo test command on Windows emits noisy [os_mon] lines to stderr. This output should be omitted.

Here's an example run:

     Running target\debug\actions-660b01cc45c8e1bd.exe

running 6 tests
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
[os_mon] win32 supervisor port (win32sysinfo): Erlang has closed
test create_document_ok_with_document_id ... ok
test read_document_nok_not_found ... ok
test create_database_ok_with_default_options ... ok
test create_document_ok_default_options ... ok
test read_document_ok_default_options ... ok
test create_document_nok_document_conflict ... ok

test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured