Html: workaround for innerHTML mXSS vulnerability [Closes nette/nette#1496]

IE8 for code `<div attr="``foo=bar">` produces invalid innerHTML `<div attr=``foo=bar>`. Adding a space at the end of the attribute forces IE to put quotes around the attribute.

More info:
http://www.nds.rub.de/research/publications/mXSS-Attacks/
http://www.slideshare.net/x00mario/the-innerhtml-apocalypse
RobotLoader: ignores ClassName::class syntax [Closes nette/robot-loader#1]
Latte: Parses respects HTML specification for HTML comments tokenization
Latte: improved HTML comments escaping
Latte: BlockMacros: fixed including parent block multiple times [Closes nette/latte#18]
iconv_set_encoding() is deprecated since 5.6.0

5.6.0 breaks loader.php in Nette 2.0
Travis: enable running tests on PHP 5.6
tests: added missing assertions, updated to Tester 1.1
readme.md: added badge and link to Packagist
Released version 2.0.15