jhm/naming: Make a simple holder type alias for extension lists
Move GetCwd to base/path_utils.h
jhm/naming: Remove unnecessary check now that GetCwd is tested to not have a trailing '/'
base/stl_util: Wrap STL pop() to make it convenient
Allow <base/thrower.h> to throw exceptions which don't define GetDesc

This makes it so that standard exceptions can be used with <base/thrower> directly.

Also add a unit test for throwing standard exceptions.
Remove FindOrElse function.

No one uses it, and it's equivalent to .at() with C++11. Thanks @mpark
Merge pull request #85 from cmaloney/misc_work

Lots of miscellaneous changes