twitter buttons added

https://dev.twitter.com/docs/tweet-button
fixes
added more info
content added
Added alt Attributes for WCAG A to header-logo
Added alt Attributes for WCAG A to splash-holder
added links to "Android Device Manager"
Fixed closing " typo
added link to https://protect.blackberry.com
added strong to Blackberry Protect
added url to Find My iPhone and changed style
Fixed " typo
Change preview of "Find my phone" feature
fix typo
Fix Safari bug
Fix Safari bug attempt 2
fix logo attempt 3
Fix Safari bug on small screens
fixed headers on safari
added noscript tags and improved alt text