Add 1.8.0 for C-based languages to interop matrix

Add 1.8.0 for C#, PHP, C++, Ruby and 1.8.1 for Python

(Node specifically left out because of failures on 1.7.2
 leaving it for another PR)

tools/interop_matrix/client_matrix.py

@@ -77,6 +77,9 @@ LANG_RELEASE_MATRIX = {
         {
             'v1.7.2': None
         },
+        {
+            'v1.8.0': None
+        },
     ],
     'go': [
         {
@@ -155,6 +158,9 @@ LANG_RELEASE_MATRIX = {
         {
             'v1.7.2': None
         },
+        {
+            'v1.8.1': None  # first python 1.8 release is 1.8.1
+        },
     ],
     'node': [
         {
@@ -204,6 +210,9 @@ LANG_RELEASE_MATRIX = {
         {
             'v1.7.2': None
         },
+        {
+            'v1.8.0': None
+        },
     ],
     'php': [
         {
@@ -227,6 +236,9 @@ LANG_RELEASE_MATRIX = {
         {
             'v1.7.2': None
         },
+        {
+            'v1.8.0': None
+        },
     ],
     'csharp': [
         #{'v1.0.1': None},
@@ -248,5 +260,8 @@ LANG_RELEASE_MATRIX = {
         {
             'v1.7.2': None
         },
+        {
+            'v1.8.0': None
+        },
     ],
 }