README Fixes

I submitted three issues ( #189, #190 & #191 ) to your GIT Issues and this is an edit on the README to correct a few mistakes mainly with the manual install instructions.

I've made some minor edits that I've found as I go on and attempt to manually install WebIDE, I'm still getting errors but these are at least a few step forward.

My Setup:
OS: Custom Raspbian (Debian Wheezy 3.6.11) with lots stripped out.
SD: 16GB Class 6