In H265Parser::ParseSliceHeader, the parser does not handle
byte_alignment() from the spec. byte_alignment() reportedly contains
at least one bit, which is not handled right now.
See Section 7.3.2.12 Rec. ITU-T H.265 v3 (04/2015).
Also added a few size sanity checks in H265Parser to make sure the
code does not crash if an invalid input is provided.
Fixes#383.
Change-Id: I33b31396058fc5ba67a0fc119be5fe56ec9443b0