v0.0.21 All Shiftr special characters should be escapable

Primary driver is users wanting to be able to use Jolt Shiftr to process Json-LD flavored documents.

See this test for examples.
https://github.com/bazaarvoice/jolt/blob/c8e6ce62a2ea7551333d666d16ddba9f11feb7c4/jolt-core/src/test/resources/json/shiftr/escapeAllTheThings.json

Note that, because Java, the "backslash" as to be doubled.