Bug 1073515: report the complete symbol correctly. r=dhylands

To remove the source file path and source line components from the
breakpad resolved symbol, we used a simple string split operation
separated by whitespaces. This had a side effect when the symbol
itself contained white spaces.

We now preserve the source file and line number information, but we use
only the basename path for symbol location info.
Merge pull request #391 from walac/bugz/1073515

Bug 1073515: report the complete symbol correctly.