Depend on rust-osdev/bootloader and rust-osdev/x86_64

Fix travis build

Fix alloc API breakage

Debug travis

Support larger allocations

Allocate PageInfo array before setting up PMM

Upgrade acpi crates

Fix slob allocator and integrate aml_parser crate

Add ACPI table parser

Improve block merging

Basic SLOB block merging; fix linker script

Add basic SLOB allocator (no block merging)

Support freeing in buddy allocator and add GDB script

Update bootloader to work with bootimage 0.7.7

Install bootimage from crates.io in travis