play nice with permissions and save page titles too

[csabahenk]

Import functionality is broken on FF 51. ATM I'm not sure if I broke it or was it broken anyway. If you consider merging this pull request, I'll take the effort to fix it up if I'm to blame for the breakage.

[mortalis13]

Hi. Thanks for your contribution. Sorry for this delay. Now I have a little bit of time to dedicate it to my adons. I'll change the structure of the repo, so it only contains the code and XPI is in the Releases. Regarding your changes:

• I'd change the path '/sdcard/Android/data/org.mozilla.firefox/files/tabs_backup/' to something shorter, don't know how to reproduce the permissions problem. Did you try it with a folder directly in the internal storage (say '/sdcard/tabs_backup')?
• on line 97 I guess it should be return s.split(/\n/)[1]; (at least without return it gives you an array of undefined elements)
• for the date/time string I'll add dashes but the colons need to be deleted cause you cannot copy it to a Window OS as the colon is not allowed there.

Later I'll add these changes, so if you want you could re-fork.