Improve the maintenance page error message

Updated: Comment #42

Problem/Motivation

The default/fallback error message includes the words "unknown error" and should be modified to make a little more sense.

Proposed resolution

Make the error message incredibly simple but translatable in both instances.

Remaining tasks

1. Determine the translatability in both cases.
2. Decide on the language to be used.
3. Preform a Beta Evaluation

User interface changes

Changes to the string which appears.

API changes

none

Original report by @chx

The website encountered an unexpected error. Please try again later.
Really. Because there are expected errors, right? Are we trying to get on the DailyWTF?