Allow to alter path in code review ignores

Currently in the my_module.coder_ignores.txt files, you have to specify the full path to the module installation.

Thus, on my dev installation it may be sites/dev.mysite.com/modules/specific/mymodule/ but on my QA environment it may be sites/qa.mysite.com/modules/specific/mymodule/ or anything else. Then because i did specify sites/dev.mysite.com/modules/specific/mymodule/ path in coder_ignores file, coder reports me lines i did ignored.

Then i would have allow the hook_coder_ignores to prefix lines with his own path. To be backward-compatible, i would have set it as argument in the returned array.

See attached path for my solution.