Ignore some jbundler related working state
Support passing in a topic for every #push in MRI

This commit also fixes a memory leak with the JRuby version of the gem where we
were not properly cleaning up children objects and holding onto references of
them forever

Fixes #46
Add a much more verbose download_file_http method for mini_portile

This should help isolate the bug we're seeing in #40 which seem to stem from
GitHub serving invalid packages
Avoid adding non-existent children to our internal list.

This really only affects testing where we might be returning nil after a
push_single expectation has been met
Merge pull request #51 from rtyler/mri-multi-topics

Multiple topics for MRI
Properly propagate the optionally passed in topic on #push when recursing through Arrays

This commit also moves tests back out of the platform specific scope and makes
the internal #push_single API more consistent to alllow easier testing.

Fixes #49
Merge pull request #53 from rtyler/fix-49

Properly propagate the optionally passed in topic on #push
Treat empty Content-Length headers as retryable errors for mitigating github.com brokeness

Periodically we'll get 200 OK responses with not Content-Length header when
trying to download from github.com, this will treat it as a retry

Fixes #40