Fix ground types 'hills' & 'canyon' not using seed

There was an issue where the ground types of 'hills' and 'canyon' were not using the seed. Based on issue #44, it seems that the intention was to use the seed to keep the layout consistent similar to the other ground types, 'noise' and 'spikes'. Below is an explanation of the steps I took to fix the issue:

Added custom seed as a parameter to the perlin object in the updateGround function
- With this change, if the case that "hills" or "canyon" are used, the seed is being passed into the perlin.noise method.
In the Perlin Noise Generator, I created a variable called randomWithSeed that will be used in the for loop to generate random numbers using the seed.
- This logic was essentially taken from the random function defined earlier in the code
- In that same for loop, I replaced r.random(666) with the new randomWithSeed variable
- Since the r variable is no longer used, I simplified the function by removing it as a parameter and as well as the line if (r == undefined) r = Math;, which isn't needed.
- I added seed as a parameter so we can pull in the user's custom seed when generating the randomWithSeed number.

Fixes Issues

supermedium / aframe-environment-component

Fix ground types 'hills' & 'canyon' not using seed #70