The first heap page (0x0) is a valid and usable page for now.

When checking the starting page from heap_get_start_page(), we need to
take that into account, otherwise we'll always return the first 0x0 page
as the allocated page.
This makes the users to always get 0x0 as the allocated region.

We loose the possibility for error checking here, so we'll need to
rework this API so we can get an error check.

Signed-off-by: Carlos Maiolino <cem@toxiclabs.cc>

Add a simple API implementing a heap memory area.

This specifies 2 main data structures:
	struct heap - Defines a heap:
		Holds a table with all entries in the specific heap and
		the initial heap memory address

	struct heap_table - Describes the usage state of every PAGE
			    within the specific heap.

Signed-off-by: Carlos Maiolino <cem@toxiclabs.cc>