Change naming from Bluemix to IBM Cloud

[kgb1001001]

We should update this to use the new ibmcloud CLI instead of the older bx cli. Other than globally replacing "bx" with "ibmcloud" there shouldn't need to be any other change. I just ran through the tutorial and verified that it all works when making that global replacement. Also, in the section on setting up an account, it's still using the word "Bluemix" instead of "IBM Cloud".