Update README.markdown

I do think recent changes changed nvm to .nvm.
Update README.markdown
Install script no longer depends on git to be installed.

Also fixed a bug where a literal "\n" would be injected into the bash profile.
Moved gitless installer into its own file.
Fix newline issue in install.sh
* Using raw.github.com instead, downloading only nvm.sh
* tar no longer required
* TARGET was not converted to DIR
* NVM_TARGET renamed to NVM_DIR (this will ensure that any locally
* existing nvm copy will be picked up and updated)
Merge pull request #250 from ronkorving/gitless

Git-less installation script
Merge pull request #251 from stelcheck/NVM_DIR

* NVM_TARGET renamed to NVM_DIR
Merge pull request #238 from shibukawa/patch-1

Update README.markdown
Merge pull request #219 from techdives/patch-1

Update README.markdown
Updating ~/nvm to ~/.nvm
Updating 0.8 references to 0.10
Updating copyright year
Merge pull request #252 from ljharb/fix_readme

Fix readme
Using source instead of dot.
Merge pull request #253 from ljharb/update_readme

Using source instead of dot. Closes #211.
Add sh directive and replace bash function with sh function.
Fix style, opening curly brace on the same line as function declaration.