enable JaegerMonkey features on mozjs185

closes COUCHDB-1376
also trap SIGINT when running js tests
Avoid badmatch when replicator dbnames have leading slashes.

Closes COUCHDB-317

Patch by Joan Touzet.
add missing dependecies
add another missing dependency.
typo
Squashed merge of 1569-feature-low-disk-space-warn:

commit de76884544f95fdaf3492a2f88899d7e1fd41326
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 10:34:04 2013 -0800

    export the new warn log funs

commit e71cf0499788553f457275558aaf3658fd74fe81
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 10:33:15 2013 -0800

    fix mistake in ?LOG_WARN

commit 5abc82b79e93a089b942dfabefb57e57fc243207
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 10:12:58 2013 -0800

    change low disk space message to warn level

    closes COUCHDB-1569

commit a1461a2b92f8cbd89f0aebe7339e754836d14202
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 09:59:03 2013 -0800

    add a ?LOG_WARN and warning level for couch_log
(COUCHDB-1305) isolate db process crashes

Merge of 1305-fix-isolate-db-crashes

[@davisp: I'll keep doing this nonsense until we allow merge commits!]

Note that there was previously a small error where couch_sys_dbs ETS
table was being searched for a #db record rather than the db name.

That's fixed here because I saw it. Sorry for not making it a
separate commit.

Squashed commit of the following:

commit f9e4e8a6e426d1569fac4cd707bbd393b102147d
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 06:28:20 2013 -0800

    don't handle case clause when death happens anyway

    Presumably the reason for the process exit is already logged by
    the exiting process (unlike an unexpected message of another sort
    which may not have been logged already).

commit 10a052a3eddbd7e89b553966895ee38a9ce439d4
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 06:25:23 2013 -0800

    consolidate two similar handle_info clauses

commit 6f3feb09e347dfe0c6812fd71e3f40d15d8d1ced
Author: Randall Leeds <randall@apache.org>
Date:   Sat Jan 26 04:35:35 2013 -0800

    isolate db process crashes in couch_server

    closes COUCHDB-1305
fix multipart response mixup, fixes replication.js