Consider switching to goblin for ELF support

[danielocfb]

We may want to consider switching to using the goblin crate for our ELF parsing needs. As per my understanding it is stable and used in many contexts. Doing so could also help with issues such as #64 and #53. The reasons for rolling our own ELF parser were somewhere along the lines of performance, but never backed by data to the best of my knowledge.

[danielocfb]

Oops, I meant to write goblin, as that's the main ELF crate in the Rust eco system. gimli is for DWARF.