Fix two issues (try 2)

This is a redo/adjustment of PR #511

* https://github.com/saintnicster/FTBLaunch/commit/22b0c235a4d2e60254a589c0c5d7683e2bb5fce5
LauncherStyle file not opening/saving correctly on OS X/*nix.  Same basic issue as PR #509.

[Console log (different)](http://pastebin.com/Pten1Wkw)
>[15:26:20] [WARN] FileOutputStream.open:-2->LauncherStyle.load:76: Could not save style: java.io.FileNotFoundException: /Users/nickfajardo/ftb/Direwolf20/Library/Application Support/ftblauncher/launcher_styles/defaultStyle.cfg (No such file or directory)
		java.io.FileOutputStream.open(Native Method)
		java.io.FileOutputStream.<init>(FileOutputStream.java:194)
		java.io.FileOutputStream.<init>(FileOutputStream.java:145)
		net.ftb.data.LauncherStyle.load(LauncherStyle.java:74)
		net.ftb.data.LauncherStyle.load(LauncherStyle.java:46)
		net.ftb.data.LauncherStyle.<clinit>(LauncherStyle.java:30)
		net.ftb.util.StyleUtil.loadUiStyles(StyleUtil.java:9)
		net.ftb.mclauncher.MinecraftFrame.<init>(MinecraftFrame.java:33)
		net.ftb.mclauncher.MinecraftLauncher.main(MinecraftLauncher.java:194)

[LauncherStyle.java#L23](https://github.com/Slowpoke101/FTBLaunch/blob/master/src/net/ftb/data/LauncherStyle.java#L23)
Fix - Cache the System.getProperty("user.home") in a class-wide static method on OSUtils and use that in OSUtils.getDynamicStorageLocation().  This should fix any other instances where files may need to be read/written (after the MinecraftLauncher class has been called)

* * * 
* https://github.com/saintnicster/FTBLaunch/commit/df7a8ad08c8ae06b3b7448c6c0508eee1cdbbe3f
Split possible multiple arguments into multiple lines of argument list