Load metadata for arguments PRIOR to integrating them into the ideal tree

[iarna]

In fact, we should load these before even loading the current tree. This let's us error AS SOON AS POSSIBLE when the user has typoed a module name / url to install.

Further, knowing the actual module name to be installed let's us be clever on global installs and eliminate anything not named from the currentTree prior to even cloning it. This is safe with global installs because globals flattened to the module being installed, not to the global node_modules folder, and as such aren't allowed to interact

It wouldn't be implausible to just call read-package-tree once for each of the effected globals, saving ourselves from even having to readdir your global node_modules.

[iarna]

Fixed in v3.1.1

(@aredridel \o/)