for packaging in hex

Fix ibrowse_http_client.erl

Fix misprint in #130

Digest could mean HTTP Digest Authentication which is completely
different from what we call Digest currently. Renaming this is
essential to implement the actual HTTP Digest Authentication

Build under R18 #129

removes doubled repl prompt

Add max_attempts option

Missed in original work.

Connections warned of badargs to ets:delete
when shutting the server down with open connections;
created noise while reviewing test results.

Algorithm change had bug where ets:select return
value was incorrectly assumed to be the object key
and not the entire object causing the following
delete attempt based on a matchspec and the key to fail.

This meant that ets was not updated to reflect the completed
requests on each connection and causing exaustion of pipelines
event though connections were idle.  Functional test added which
demonstrated the problem.

In prior commit, missed switch of matchspec to work
with deletes, fixed here.

Added retry logic for race conditions around lb and
conn both trying to update same record at the same time.
If more than max is experienced, just let it go, things
will probably be ok.

Added additional functional tests ensuring that
the pipelines empty and added some robustness
around the test server.