Performance & robustness improvements to tar extraction code

- Performance improvements for file creation
- Added more error handling
- Namespaced everything to avoid conflicts with other categories or other LightUntar integrations
Bumping the default auto-refresh interval up to 2 min
Merge pull request #30 from mindsnacks/feature/faster-tar

Performance & robustness improvements to tar extraction code
Improved download policy observation

Previously, the donwload policy was only checked when the task was enqueued.
Now it's checked in isReady, meaning that it's more compliant with wifi/3g changes.
Merge pull request #32 from mindsnacks/feature/improved-download-policy-observation

Improved download policy observation
Updating README
Adding missing import
Fixing tests
Ensuring tar file is a multiple of 512 bytes
Merge pull request #33 from mindsnacks/feature/defensive-tar

Ensuring tar file is a multiple of 512 bytes
Adding a convenient way to reset a policy
Merge pull request #34 from mindsnacks/feature/download-policy-reset

Adding a convenient way to reset a policy
Initial support for new "external" bundles
Patching up the demo app
Making manually registered external bundles always "active" so they're not deleted.
Merge pull request #35 from mindsnacks/feature/revamp-bootstrapping

Feature/revamp bootstrapping
missing mark
fixing typo
Error while Cloning fix

If a bundle failed to clone (for whatever reason) it's status was left at
'cloning'. This would cause Zinc to try to resume cloning again later. However,
it would keep attempting to clone the exact bundle *version*. This can be a
problem if that version was deleted. Now, if cloning fails, it sets the bundle
status back to 'None', and the regular tracking logic will pick up a new version.
Moving clone complete event outside the conditional