Fix burnin bug: Index error in pithos account_get

Bug description: pithos test assumed there are always some extra
containers in the tested pithos account and checked for their
existence, causing an Index error to be raised when starting the
test with an empty account.

Solution: Do not check for containers outside the ones created
specifically for the test.
cyclades: Fix type error

together with some PEP8 issues.
cyclades: Fix snapshots of attached volumes

Fix major bug when taking snapshots of non-root volumes. The custom
'SnapshotInstance' method of 'GanetiRAPIClient' always took a snapshot
of the root volume (index=0) of an instance, ignoring the volume that
the user requested. This resulted in always taking a snapshot of the
root volume which in many cases did not fail.
cyclades: Invalidate snapshots when job fails

Make Cyclades invalidate snapshots in case of failure to submit the job
to Ganeti, or when the job fails. In either case invalidation is
performed by marking...
TODO: Add states sto API

fixes grnet/synnefo#231
admin: Migrate from Highcharts to C3

For every chart that uses Highcharts, add its C3 counterpart below it.
The change from Highcharts to C3 is for license reasons.
admin: Lift restriction on charts

Remove `ADMIN_ENABLE_CHARTS`, as we now use C3 instead of Highcharts.
docs: Remove Admin charts section

Due to the migration from Highcharts to C3, the charts are now enabled
by default.
Revert "cyclades: Invalidate snapshots when job fails"

This reverts commit 0d1b405df358e17e369d910edc0fa9977b12bfa9 that has
been accidentally pushed remotely.
Merge branch 'release-0.16-admin-charts' of https://github.com/apyrgio/synnefo into release-0.16
admin: Fix typos in admin tests
admin: Fix typo in deleted entries tooltip

Remove the "None." string that appeared on every category (besides
projects) due to a bad template tag. Also, add the tooltip in a
separate html file for easier editing.

Fixes apyrgio/synnefo#288