OPP: Limit try scope in ObexServerSession

getHeader calls throw IOException, limit try/catch block to those calls.
Return early instead of using preReject and saving the return type.

Remove UNACCEPTABLE_SHARE_INBOUND_TYPES.  There's no point of having a
blacklist and a whitelist.

Test: File transfer sanity test
Change-Id: I64ab3a3a4f498d2e1bce5ca8a12b58660eba0dca