[TIMOB-17663][TIMOB-17684] (3_4_X) iOS8 fixes

Backport of PR #6097 into 3_4_X

Fixes [TIMOB-17684](https://jira.appcelerator.org/browse/TIMOB-17684)

Additional changes for TIMOB-17663](https://jira.appcelerator.org/browse/TIMOB-17663)

Remove UILaunchImages from tiapp.xml template and autogenerate plist entries in CLI