Update for Serbian translation

[goranvasic]

Serbian translation was missing translated strings for several menu options and tooltips. These are now covered, and also some previous translations for the UI were modified to be more "user friendly".

[goranvasic]

I can see that Travis build failed, so I submitted the contributor license agreement here http://dev.brackets.io/brackets-contributor-license-agreement.html

[RaymondLim]

@goranvasic You have some duplicate keys that are causing some linting errors.

Linting src/nls/sr/strings.js...ERROR
[L131:C41] W075: Duplicate key 'BUTTON_YES'.
    "BUTTON_YES"                        : "Да",
Linting src/nls/sr/strings.js...ERROR
[L132:C41] W075: Duplicate key 'BUTTON_NO'.
    "BUTTON_NO"                         : "Не",
Linting src/nls/sr/strings.js...ERROR
[L348:C44] W075: Duplicate key 'OK'.
    "OK"                                   : "У реду",
Linting src/nls/sr/strings.js...ERROR
[L349:C44] W075: Duplicate key 'DONT_SAVE'.
    "DONT_SAVE"                            : "Немој сачувати",
Linting src/nls/sr/strings.js...ERROR
[L350:C44] W075: Duplicate key 'SAVE'.
    "SAVE"                                 : "Сачувај",
Linting src/nls/sr/strings.js...ERROR
[L351:C44] W075: Duplicate key 'CANCEL'.
    "CANCEL"                               : "Откажи",
Linting src/nls/sr/strings.js...ERROR
[L352:C44] W075: Duplicate key 'DELETE'.
    "DELETE"                               : "Обриши",

[RaymondLim]

Where do you get this? This is not a valid SHA. You have to look up from this history page and copy the SHA from the one that you're translating for. Make sure you have the exact total line numbers in your localized file when comparing (diffing) to the English strings and also ensure that your localized file does not have keys in a different order from root/strings.js. Once you verify the order and diffing the changes properly, then you will also fix the linting issue from Travis.

[goranvasic]

@RaymondLim Could you please check the Travis CI build, it seems that it was not able to properly execute npm command. Note that I submitted my commit directly from web browser.

[RaymondLim]

@goranvasic Not sure what went wrong with npm, but I restarted the build and it should be fine this time.

[goranvasic]

@RaymondLim Thank you.

[goranvasic]

@RaymondLim I see that this pull request is still not merged so please let me know if there is anything else that needs to be done on my side.

[RaymondLim]

@goranvasic Do you have someone that can do the linguistic review?

[goranvasic]

@frennky can you please review this translation?

[frennky]

Everything looks good to me.

[goranvasic]

@frennky Thanks
@RaymondLim Is this ok to be merged now?