Fixed the request workflow when a pre-provisioning dialog is used

Several adjustments in the code were done to accommodate the
pre-provisioning dialog prior to the main provisioning dialog in the
request workflow.

https://bugzilla.redhat.com/show_bug.cgi?id=1108918
Merge pull request #113 from AparnaKarve/vm_preprovisioning_dlg_bz1108918

Fixed the request workflow when a pre-provisioning dialog is used
Optimized Metric::CiMixin#has_perf_data? method

https://bugzilla.redhat.com/show_bug.cgi?id=1086015

has_perf_data? method calls ActiveRecord exists? instead of
calling first_capture (which calls first_and_last_capture).
Merge pull request #130 from chessbyte/bz1086015_optimize_has_perf_data_method

Optimized Metric::CiMixin#has_perf_data? method