Update Mono and OmniSharp depedencies

Author: DustinCampbell

package.json

@@ -66,7 +66,7 @@
   "runtimeDependencies": [
     {
       "description": "Mono Runtime (Linux / x86)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86-4.6.1.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86-4.8.0.478.zip",
       "installPath": "./bin",
       "platforms": [
         "linux"
@@ -81,7 +81,7 @@
     },
     {
       "description": "Mono Runtime (Linux / x64)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86_64-4.6.1.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.linux-x86_64-4.8.0.478.zip",
       "installPath": "./bin",
       "platforms": [
         "linux"
@@ -96,7 +96,7 @@
     },
     {
       "description": "Mono Runtime (macOS)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.osx-4.6.1.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/mono.osx-4.8.0.478.zip",
       "installPath": "./bin",
       "platforms": [
         "darwin"
@@ -108,7 +108,7 @@
     },
     {
       "description": "Mono Framework Assemblies",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/framework-4.6.1.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/framework-4.8.0.478.zip",
       "installPath": "./bin/framework",
       "platforms": [
         "darwin",
@@ -117,7 +117,7 @@
     },
     {
       "description": "OmniSharp (.NET 4.6 / x86)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x86-1.9-beta22.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x86-1.9-beta23.zip",
       "installPath": "./bin/omnisharp",
       "platforms": [
         "win32"
@@ -128,7 +128,7 @@
     },
     {
       "description": "OmniSharp (.NET 4.6 / x64)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x64-1.9-beta22.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-win-x64-1.9-beta23.zip",
       "installPath": "./bin/omnisharp",
       "platforms": [
         "win32"
@@ -139,7 +139,7 @@
     },
     {
       "description": "OmniSharp (Mono 4.6)",
-      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-mono-1.9-beta22.zip",
+      "url": "https://omnisharpdownload.blob.core.windows.net/ext/omnisharp-mono-1.9-beta23.zip",
       "installPath": "./bin/omnisharp",
       "platforms": [
         "darwin",