made basic ScriptExecution acceptance tests run under both debug and non-debug
#775 Set loglevel when debug arg is provided

Moved the logic that sets LogLevel to debug when Debug is provided from
ArgumentParser to ArgumentHandler.

Added tests for when Debug is provided on command line and in the opts
file.

Removed test from the ArgumentParserTests that is no longer valid.
Merge pull request #821 from ryanrousseau/775

#775 Set loglevel when debug arg is provided
Add support for global opts file - fixes #768

FileSystem.GlobalOptsFile will return the path for a scriptcs.opts file
in the ModulesFolder

ArgumentHandler looks for non-default option values first from the
command line, then from a local opts file if it exists, and finally from
a global opts file if it exists.

Rename ModulesFolder to GlobalFolder per discussion on #768

Update ShouldUseScriptOptsIfParsingFailed: parser mock will create a
ScriptCsArgs instead of returning null to avoid null reference exception
force the use of trace in Mono engine and in Roslyn engine - on first execution only
separated StringExtensions into its own file
undefine should be #undef
Merge pull request #825 from filipw/feature/trace

defined TRACE
updated to Mono.Csharp 3.6.1
removed InteractiveBase from MonoHost
Merge pull request #828 from filipw/feature/interactivebase

removed InteractiveBase from MonoHost
Merge pull request #827 from filipw/feature/mono361

updated to Mono.CSharp 3.6.1
added System.Net.Http to defaults
adjusted tests
Merge pull request #829 from filipw/feature/System.Net.Http

Added System.Net.Http to defaults
Added constant for config filename
Add fix to pull out the inner exception when an AggregateException is returned from Roslny
Merge pull request #773 from ryanrousseau/opts2

#768 Add support for global scriptcs.opts file
Adding same fix for mono
Merge pull request #834 from glennblock/dev

Add fix to pull out the inner exception when an AggregateException is returned from Roslyn