Enables Rack::Deflate for notify.js

This saves a bit of time when the user tries to load the page
that has javascript notification.
It will gzip the javascript, from my calculations the gain is
up to 27Kb.
Added max-age to notifier.js

This adds some performance to the application clients,
they won't need to download it/check for each request.
Avoid same error if other line than first change

Only the first line of backtrace was use to mark error like same. Avoid
this behavior because some language ( like python ) change only last
line of backtrace
Fix environment value of problem with invalid problem already save

See #557
Merge pull request #552 from tscolari/master

Using Rack::Deflate and long expire dates for notifier.js
Update Changelog

[ci-skip]
Fix Problem with environement == {} too in old migration

See #557
show errbit version in footer
Bump version to 0.2.0
Merge pull request #563 from anicet/patch-1

Bump version to 0.2.0
Update migration to generate fingerprint in best system

See #557
Merge pull request #555 from shingara/bugs/not_same_if_change_last_backtrace_line

Avoid same error if other line than first change
Merge pull request #559 from shingara/tickets/557

Fix environment value of problem with invalid problem already save
update changelog contributors list [ci-skip]