Setup simTest Branch for cocotb

[UHCL-CENG-SeniorProject-2021]

Setup the simTest branch so both users may work with cocotb simultaneously.

[bklolo]

Merged simTest to master

• added SPI block to logic_top.vhd
• added spi2ahb.vhd and spi2ahbx.vhd from GAISLER library to the project
• updated build.tcl to generate a clean, working project with the new files