Adding caching to kpm restore

use -r or --refresh argument to force refresh of cached data
during a restore
Using the same HttpClient for all requests to a source
Fix local caching for kpm

- Add "--no-cache" flag to control use of local cache
- Add feed pagination handler and cache all pages
Small changes to project loader
- Cache the loader properly (use loader object as cache key)
- Fix order of GetLibraryExport call so that it's it calls back
into the loaders before calling the compiler itself.
Remove unzipping of nuget packages from the runtime
Return List<AssemblyDescription> for both framework and libs in nuget
Remove the .dll from the reference name.
Added support for loading Console apps
- Modified the RootHost to look for .dll as well as .exe files in the
 specified lib folders.
- Added support for invoking entry points using Assembly.EntryPoint
Updated downloading message to display actual feed URL.
Renamed Nuget API Feed variable to KRE_FEED in line with termonology from windows kvm.ps1
Only set KRE_FEED when it is not already set, allowing the user to override if necessary (in line with kvm.ps1)
Fixed return value of _kvm_find_latest and terminated kvm when _kvm_find_latest does not find a valid version in the feed
Updated packages due to changes in contracts
Fix warnings in the build
Turn on warnings-as-erros
Optimized accessing reference assemblies
- Lazily resolve a target framework at a time as well as the assemblies
within those target frameworks.
- This helps to reduce the amount of IO that happens when compiling.
Fixed typo
Merge pull request #404 from graemechristie/patch-1

Fix KVM references
Modified the command 'kvm alias foo bar' to allow alias 'foo' to be set to the verison of alias 'bar' when bar is an existing alias
Merge pull request #407 from graemechristie/patch-3

Allow kvm alias to set one alias to the version of another alias
Remove kvm from this repository
Updating System.Xml.ReaderWriter to 4.0.10.0