Added support for a private URL

In some cases, a bot may need to access the API using a different URL
than normal users would be accessing, such as using an SSL connection or
including HTTP authentication data in the URL for SOAPpy.  This patch
adds support for a private URL that is used by the bot to connect to the
API, while still using the normal URL when displaying bug data to users.

This adds a new configuration option 'plugins.Mantis.privateurlbase'.
Correct issue with new bug annoucements
Merge pull request #2 from SethAten/master

Fix issue with period bug announcements not working
Manually convert to int to fix octal issue

When relying on Supybot's built-in "int" argument conversion type, any
bug numbers pasted from Mantis that are prefixed by zeroes (eg, 000123)
get interpreted as octal numbers, which results in lookups for the
incnorrect issue.  By using Supybot's "text" conversion type, we can
then use python's int() method to force a conversion to decimal,
regardless of how many zeroes the number is prefixed with.
Whitespace cleanup