Add SimpleFlatMapper and jmh benchmark

I added the jmh benchmark for jackson, opencsv, univocity and simpleflatmapper.
I added a readme in src/main/java/com/univocity/articles/jmh that contains explanation on how to run the jmh. The maven needs to compile so I added the dependency def for

org.ostermiller
utils
1.07.00

only version I could find.

SimpleFlatMapper 0.9.8 appears to now be available on maven central.

Regards, Arnaud