Fixed default segmentation behavior for searches.

oneshot, export, and Job.events and Job.preview now use segmentation=none by default (to suppress <sg> tags in the XML output).
Fix handling of _raw field in ResultsReaders.

_raw is returned as plain text when accessed as a field on an event, and events have a new method
raw_as_xml which returns the full XML of _raw, including highlighting.
Make export tests use an ExportStream wrapped input, not just a raw file.

We weren't testing what we thought we were testing, since there is now special handling
for export streams in ResultsReader.
Make Collection#length uses Atom metadata to determine length instead of iterating over collection.
Fix path to roles collection.

Was incorrectly authorization/roles, which worked due to historical quirks in Splunk. Now it is set to authentication/roles.
Switched quotes in the list of paths to double quotes while I was in that part of the code.
Add inputs to SDK.

Refactored out a ReadOnlyCollection superclass of Collection.
Create InputKinds and Inputs classes, and add Service#inputs method.

Fixed a typo in the ResultsReader documentation.
Resolved code review comments.
Merge branch 'fross/xml_work' into develop
Started adding modular input kinds.
Merge branch 'fross/inputs' into fross/mod-inputs
Finished adding modular input kinds.
Add test for roles on users.
Update Changelog.
Resolved comments from reviews. Added tests to get coverage up. Fixed bugs found by new tests.
Add modular input kinds example. Fix error in gem spec file.
Fix request method in Context#restart.
Guard input collection "all" to only be checked on Splunk >= 5.0.
Add escape to remove errors on trying to delete sleep_command app on Windows.
Fixed behavior of detecting windows. Was detecting on the client, not the server.
Added omits to work around segmentation problems in 4.3.5 for now.