(PDB-700) Allow changes to maxFrameSize in activemq

- maxFrameSize previously defaulted to 100 MB.  Now default is 200 MB with user
  configurability.
(PDB-577) Lower KahaDB MessageDatabase logging threshold.

- Previously, premature termination of PuppetDB import under specific ownership
conditions led to a residual KahaDB lock file that could prevent subsequent imports
from running with no obvious reason why.  This patch lowers the log threshold
for KahaDB MessageDataBase so affected users are informed.
(PDB-130) Fixes a nasty traceback exposed when users run import from command line with an invalid filename. A friendly message is now printed instead.
(PDB-697) Document and test new events and resources features

This change adds tests and docs for events/resources features inherited
by the switch over to the query engine.

This change also documents and tests an explicit "null?" operator. Some
endpoints for v2/v3, when using not, such as ["not" ["=" "line" 10]]
would return line values that were NULL in addition to other line
numbers. In v4, this is no longer the behavior. Users wanting null
values in addition to lines != 10, can use "null?" with an "or"
statement.
Merge pull request #989 from wkalt/ticket/master/pdb-700-max-framesize

(PDB-700) Allow changes to maxFrameSize in activemq
Merge pull request #990 from wkalt/ticket/master/pdb-130-no-file-on-import-message

(PDB-130) Replaces traceback exposed when puppetdb import is passed a missing file.
Merge pull request #991 from wkalt/ticket/master/pdb-577-KahaDB-lock-file-broker-failure

(PDB-577) Lower KahaDB MessageDatabase logging threshold.
Merge pull request #992 from senior/ticket/master/pdb-697-doc-test-changes-for-qe

(PDB-697) Document and test new events and resources features
(PDB-337) Remove extraneous _timestamp fact

Previously a _timestamp fact was submitted to puppetDB even though _timestamp
was originally intended for internal use.  This commit strips internal data
(all preceded by "_") from the factset before submission to PuppetDB.
Merge pull request #993 from wkalt/ticket/master/pdb-337-fix-_timestamp-fact

(PDB-337) Remove extraneous _timestamp fact
(PDB-220) Coerce numerical function output in manifests to string

Previously, when a user defined a numeric-valued function in a puppet manifest
and submitted it to notify, the resource-title would remain numeric and
PuppetDB would throw exceptions while storing reports. Per the docs,
resource-title must be a string. This pull request avoids the problem by
coercing resource-title to string.
Merge pull request #994 from wkalt/ticket/master/pdb-220-report-storage-numeric-functions

(PDB-220) Coerce resource-title to string
(PDB-240) Replace anonymize.clj read-string with clojure.edn/read-string

This patch replaces a call to read-string in anonymize.clj with a call to
clojure.edn/read-string. Unlike clojure.core/read-string,
clojure.edn/read-string is safe to use with untrusted data and guaranteed to
be free of side-effects.
(RE-1497) Remove quantal from build_defaults

This commit removes quantal from all build defaults because it is end of
life. It removes the defaults from the build_defaults yaml.
Merge pull request #995 from clantant/RE-1497/master/srcs

(RE-1497) Remove quantal from build_defaults
Merge pull request #996 from wkalt/ticket/master/pdb-240-swap-anonymize-read-string

(PDB-240) Replace anonymize.clj read-string with clojure.edn/read-string
(RE-1497) Remove quantal from build_defaults

This commit removes quantal from all build defaults because it is end of
life. It removes the defaults from the build_defaults yaml.
Merge pull request #997 from clantant/RE-1497/stable/srcs

(RE-1497) Remove quantal from build_defaults
(PDB-164) Add documentation for select-nodes subquery operator

This pull request supplies V4 API documentation for the select-nodes subquery
operator, which was previously supported but undocumented.
Merge pull request #998 from wkalt/ticket/master/pdb-164-select-nodes-documentation

(PDB-164) Add documentation for select-nodes subquery operator