It is common in constrained circumstances to prefer an empty string
result from JSONPath templates for missing keys over an error. Several
other implementations provide this (the canonical JS and PHP, as well as
the Java implementation). This also mirrors gotemplate, which allows
Options("missingkey=zero").
Added simple check and simple test case.
Automatic merge from submit-queue
Cleanup third party (pt 2)
Move forked-and-hacked golang code to the forked/ directory. Remove ast/build/parse code that is now in stdlib. Remove unused shell2junit
