Fix event listeners & zepto

[techfg]

Explain the details for making this change. What existing problem does the pull request solve and/or what capability does it add?

Resolves #338 - Fix event listeners
Resolves #339 - Fix Zepto compatibility

Test plan (required)

1. All tests pass and all examples work with both jQuery & Zepto builds including using jQuery or Zepto with Zepto build.
2. Module loading via all UMD loaders (e.g. AMD/CJS/etc.) works as expected for both zepto & non-zepto IM builds and for zepto build, using either zepto or jquery as dependency.