- fix source url

- update to 0.8.6:
- Errors which occur within the Mako render step are now intercepted
and raised as CommandErrors like other failure cases; the Mako
exception itself is written using template-line formatting to
a temporary file which is named in the exception message.
- Added a fix to Postgresql server default comparison which first checks
if the text of the default is identical to the original, before attempting
to actually run the default. This accomodates for default-generation
functions that generate a new value each time such as a uuid function.
- Fixed bug introduced by the fix for :ticket:`338` in version 0.8.4
where a server default could no longer be dropped in batch mode.
Pull request courtesy Martin Domke.
- Fixed bug where SQL Server arguments for drop_column() would not
be propagated when running under a batch block. Pull request
courtesy Michal Petrucha.