couch_replicator_scheduler_job using random module

[wohali]

Current Behaviour

When attempting a CouchDB build using Erlang 20, the following warnings are emitted:

==> couch_replicator (compile)
/home/joant/couchdb/src/couch_replicator/src/couch_replicator_scheduler_job.erl:113: Warning: random:seed/1: the 'random' module is deprecated; use the 'rand' module instead
/home/joant/couchdb/src/couch_replicator/src/couch_replicator_scheduler_job.erl:471: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead

Expected Behavior

We should emit no warnings during compile.

Possible Solution

Something similar to the now-removed couch_crypto module approach is probably necessary, see
https://github.com/apache/couchdb/pull/681/files#diff-d638c36d558ae9f19898014029c6007f

Context

Trying to finish cleaning up CouchDB for OTP-20 compatibility.

[wohali]

Note that the khash test suite uses this extensively, too:

test/gen_term.erl:56: Warning: random:uniform/0: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:65: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:70: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:78: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:83: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:84: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:88: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:89: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:102: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
test/gen_term.erl:110: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead
Compiled test/gen_term.erl
test/khash_test.erl:3: Warning: export_all flag enabled - all functions will be exported
test/khash_test.erl:86: Warning: erlang:now/0: Deprecated BIF. See the "Time and Time Correction in Erlang" chapter of the ERTS User's Guide for more information.
test/khash_test.erl:86: Warning: random:seed/1: the 'random' module is deprecated; use the 'rand' module instead
test/khash_test.erl:370: Warning: random:uniform/0: the 'random' module is deprecated; use the 'rand' module instead
test/khash_test.erl:382: Warning: random:uniform/1: the 'random' module is deprecated; use the 'rand' module instead

[nickva]

Fixed