Allow parameter to appear in values if escaped

I am using an inifile format to put some gem-esque version restrictions, a bit like:

```
[production]
web-api = ">= 1.4"
```

which reads OK, but if you try and write it out, it fails to quote or escape, which then fails to be read.

The commit I've written escapes the equals sign (wikipedia seemed to say that was a recognised escape for ini files), which also reads back in correctly.


Cheers,
Nick