Add shorthand version of expose meta data

[gzmask]

Instead of having to do (defn ^{:expose :foo} foo ...), can we just do `(defn ^expose foo ...) instead? Also defaulting the expose name to be same as function name.

[kumarshantanu]

I think (defn ^:expose foo ...) (^:expose rather than ^expose) is already supported. In fact, if any of the arguments has an :inject tag then :expose tag is automatically inferred for defn.

[gzmask]

Nice! My bad not finding that out, hope this bit got documented soon.

[kumarshantanu]

Actually, this bit is sort of alluded to in this section: https://github.com/kumarshantanu/dime/blob/master/doc/intro.md#understanding-injection-annotations