Add ordered aggregate IModuleLoader

[Oceanswave]

Similar to the AggregateModuleLoader except that

• No Prefixes
• Registered Module Loaders denote a priority, such that if a higher-priority module loader fails to find a module with a given specifier, it attempts to load from the lower-priority loader

e.g.
loader0 - webresource moduleloader
loader1 - github moduleloader
loader2 - assembly moduleloader

import foo from 'super-man'

1. checks the webresource for a 'super-man.js' resource module
2. checks the github module loader for a 'repository/super-man.js' resource module
3. checks the assembly module loader for a 'super-man' module