Update mybatis & use slf4j-simple for logging tests

Update mybatis from 3.2.7 to 3.2.8
Add slf4j-simple in test scope to get rid of warnings about slf4j
binding during build.
Fix slf4j api and add missing btm scope test

slf4j was coming from btm.  So fixed it to use matching api to simple
impl.
btm was listed in test section but was missing scope which meant it was
compile and transcient if anyone uses mybatis-cdi so fixed that to test
scope so the test dependency is no longer picked up by mistake.
Merge pull request #8 from hazendaz/master

Update Mybatis, clear build warnings, and fix dependency.