Tag filter support

[vers-one]

This pull request:

1. Adds support for the tags optional input parameter to filter version declarations within matching files.
2. Updates regular expressions for AssemblyInfo* plugins which now require the attributes to be at the beginning of the line (after trimming whitespaces). This allows the plugin to skip the commented lines.
3. Adds an error message if there are two or more occurrences of the same version declaration found in a single file.
4. Adds the backward slash (\) to forward slash (/) replacement for the file / files input because fastGlob doesn't support backward slashes.
5. Moves test input files into separate directories (one per integration test), so the tests can be run simultaneously.