Merge pull request #726 from adamralph/replcommands

Replcommands
red (mono): added ScriptExecution.ScriptThrowsAnException and switched to runtime Mono conditional
green (mono): removed swallowing of script exceptions
build: added .travis.yml, build.sh and fixed up test projects
build: removed legacy package restore artifacts and updated to NuGet.exe 2.8.2
build: fixed NuGet.Core path casing and increased xbuild verbosity
use all namespaces not default ones
prevent wrapping ScriptResult in ScriptResult (if command executes code this could happen)
added test
do not print null scriptresult
Merge pull request #739 from adamralph/mono-build

Mono build on Travis CI
Merge pull request #741 from filipw/bugfix/replcommandcleanup

Prevent wrapping ScriptResult in ScriptResult in REPL commands
Merge pull request #735 from adamralph/mono-script-exception

Removed swallowing of script exceptions in Mono
Added build status badges :sparkles:
readme - statuc -> status
refactor: replace file system constants with IFileSystem
build: reverting mis-committed CommonVersionInfo.cs (from July 2013)
add Linux build instructions to readme
Merge pull request #738 from adamralph/replace-filesystem-constants

replace file system constants with IFileSystem
Updated PackagesFile, PackagesFolder, BinFolder, DllCacheFolder, NuGetFile to be virtual