Hello, if you are a former web developer how about having a look into SAPUI5 here at SAPUI5 SDK - Demo Kit and the OpenSource equivalent OpenUI5.
SAP has build its own web apps -> known as SAP Fiori: http://experience.sap.com/fiori/
Here is a friendly guide to build a "Fiori like" app:
Building SAP Fiori-like UIs with SAPUI5 in 10 Exercises
Don't get lost in details, focus on the web app source code and the pdf.
There is an upcoming (free) openSAP Course for this whole User Experience:
Course: Introduction to SAP Fiori UX
I think you could work then as a developer at IT consulting company who are looking for SAPUI5 developers (I did as engineer/consultant/developer hybrid) or you could work at SAP as a JavaScript/SAPUI5 (I joined in July 2014).
Currently there are no certifications for SAPUI5 available, just one training:
WDE360 - Developing UIs using HTML5 and SAPUI5 | SAP Training and Certification Shop
Very expensive, I attended the predecessor WDE350, and it is more a focus on the normal controls, not that much on the sap.m library (which is used in Fiori) and focuses not really on app building, better try the SAPUI5 10 exercises first.
Personal opinion:
For sure you can make lots of money as a consultant, but it is a looong and a hard journey and SAP ecosystem is VERY big and in mobile can include everything (security, multi-tentant, multiple-systems, failover, user synchronization authentication....).
But if you love developing you can also make a great career and you have the education for that - and this is my path! Maybe later you can be a development architect if you'd like.
Happy coding!