Send a shortened $0 as application_name to the server in order to
avoid warnings about truncated identifier.

Thanks to Svoop for this report.

--HG--
branch : v0.15-stable
Send a shortened $0 as application_name to the server in order to
avoid warnings about truncated identifier.

Thanks to Svoop for this report.
Update History.rdoc.

--HG--
branch : v0.15-stable
Update PG::Connection documentation
Merge with v0.15-stable
Bump the patch version
Added signature for changeset 0bfb6ff650be
Added tag v0.15.1 for changeset 4692c20bcbde
Fix date in History
Avoid warnings about uninitialized instance variables
Return result of the block in conn#transaction instead of nil. This fixes issue #158 .