Re-organized installation instructions in two steps
Link to documentation is relative
Fix in relative link
Fix in relative link (2)
Rewrote installation doc
Small fixes
Relative links
Added note on composer.json
Some fixes according to PR notes
Merge remote-tracking branch 'doc/master' into 1.3

Conflicts:
	README.markdown
Merge branch '1.3'

Conflicts:
	README.markdown