Invitation shown as "Unknown" when sent from EAS account and received sending failure...

Invitation shown as "Unknown" when sent from EAS account and received sending failure server email and tried to open it from .eml attachment.

[Problem] Invitation shown as "Unknown" when sent from EAS account and received sending failure server email and tried to open it from .eml attachment.
[Cause & Measure] Cause: In parsing mime, "unknwon" is set as its name before checking content subtype as "calendar".
Measure: Checking content subtype first if it is calendar then set its name as "unknown" if it is not calendar type.

Change-Id: I2ba5ee8368d397b152d395db1e073e9d290c672d
(cherry picked from commit 0b852a62cfab550334d367cf8d5f5f93b71c107f)