Add installation script to simplify setup on windows. Modified README.

Author: costleya

README.rst

@@ -35,15 +35,29 @@ Installing git-secrets
 ~~~~~~~~~~~~~~~~~~~~~~
 
 ``git-secrets`` must be placed somewhere in your PATH so that it is picked up
-by ``git`` when running ``git secrets``. You can use ``install`` target of the
-provided Makefile to install ``git secrets`` and the man page. You can
-customize the install path using the PREFIX and MANPREFIX variables.
+by ``git`` when running ``git secrets``. 
+
+**\*nix (Linux/OSX)**
+
+You can use ``install`` target of the provided Makefile to install 
+``git secrets`` and the man page. You can customize the install path
+using the PREFIX and MANPREFIX variables.
 
 ::
 
     make install
 
-Or, installing with Homebrew (for OS X users).
+**Windows**
+
+Run the provided install.ps1 powershell script. This will copy the needed files
+to an installation directory ("%USERPROFILE%/.git-secrets" by default) and add
+the directory to the current user PATH.
+
+::
+
+    PS > ./install.ps1
+
+**Homebrew (for OS X users).**
 
 ::
 

install.ps1

@@ -0,0 +1,48 @@
+Param([string]$InstallationDirectory = $($Env:USERPROFILE + "\.git-secrets"))
+
+Write-Host "Checking to see if installation directory already exists..."
+if (-not (Test-Path $InstallationDirectory))
+{
+    Write-Host "Creating installation directory."
+    New-Item -ItemType Directory -Path $InstallationDirectory | Out-Null
+}
+else
+{
+    Write-Host "Installation directory already exists."
+}
+
+Write-Host "Copying files."
+Copy-Item ./git-secrets -Destination $InstallationDirectory -Force
+Copy-Item ./git-secrets.1 -Destination $InstallationDirectory -Force
+
+Write-Host "Checking if directory already exists in Path..."
+$currentPath = [Environment]::GetEnvironmentVariable("PATH", "User")
+if ($currentPath -notlike "*$InstallationDirectory*")
+{
+    Write-Host "Adding to path."
+    $newPath = $currentPath
+    if(-not ($newPath.EndsWith(";")))
+    {
+        $newPath = $newPath + ";"
+    }
+    $newPath = $newPath + $InstallationDirectory
+    [Environment]::SetEnvironmentVariable("PATH", $newPath, "User")
+}
+else
+{
+    Write-Host "Already in Path."
+}
+
+# Adding to Session
+Write-Host "Adding to user session."
+$currentSessionPath = $Env:Path
+if ($currentSessionPath -notlike "*$InstallationDirectory*")
+{
+    if(-not ($currentSessionPath.EndsWith(";")))
+    {
+        $currentSessionPath = $currentSessionPath + ";"
+    }
+    $Env:Path = $currentSessionPath + $InstallationDirectory
+}
+
+Write-Host "Done."