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