Add isPending, deprecate isResolved

Fixes #164
Migrate isResolved to isPending in specs
Merge pull request #166 from kriskowal/is-pending

Add isPending, deprecate isResolved
Merged v0.8 into v0.9 (master)
Remove deprecated isResolved
Undeprecate invoke.  Battle left for later.
Support post with no args for function application
Remove deprecated put, use set