GEOMESA-140 Warn users about missing temporal component of index

This commit adds a warning when a user neglects to properly set SF_PROPERTY_START_TIME in the UserData. Such a mistake is non-fatal, but does impact performance.
I'd see if you could use string interpolation with this.  E.g....

``` 
   |However, the following attribute(s) could be used in GeoMesa's temporal index:
   |${matches.mkString("\n", "\n", "\n")}
   |Please note that while queries on ...
```