Update readme.md

Add `-Scope CurrentUser` to `Set-ExecutionPolicy` call due to changes in PowerShell 3.

Thanks for the tip, Josh!
Hide error if ~/.ssh doesn't exist
Hide error message if ~/.ssh doesn't exist
Kill trailing whitespace
Refactor writing branch to prompt
Export Write-Prompt for use in custom scripts
Remove Write-Prompt -NoNewLine switch
Add default for Write-Prompt -BackgroundColor
Rename Coalesce-Args to Invoke-NullCoalescing

PowerShell complains if modules export invalid verbs
Export Get-SshAgent

Closes #70
updated year on license. aka OCD
changed Add-SshKey to prefer the HOME-EnvVar over the UserFolder ~

OpenSSH and Git uses the folder defined in the HOME Environment Variable, if declared, instead of ~\. Now also Poshgit support these.
Avoid mistaking NuGet for PowerTab

http://stackoverflow.com/questions/13215766/installing-posh-git-in-visual-studio-package-manager
Update prompt to use $pwd.ProviderPath

Suggested by @rpardee (#75)
Update path to TortoiseProc to reflect rename.

TortoiseGit 1.8.0 renamed TortoiseProc to TortoiseGitProc, which caused a
bug in posh-git where calling tgit would throw an exception (could not
find TortoiseProc.exe).

This commit fixes that bug, by testing whether TortoiseGitProc exists and
using that if it does.  If it does not exist, then the default
TortoiseProc is used instead.
Add .gitattributes/.gitignore
Update readme.md

Closes #81
Stop error message when id_rsa is missing

Since we set the $Env:HOME when we launch our Git Shell, we hit 
this new code path which joins that path with the .ssh\id_rsa file.
Problem is, that file doesn't exist so we get ssh-add taking a long 
time and reporting an error.

This code path should do the same thing as the old one and return 
null if the file doesn't exist.
Support for "git flow" added

Closes #76
Added file tab expansion for diff/difftool and merge/mergetool

Closes #48