[Janitor] Bump version on master to 1.7.0prealpha

VERSION.cmake

@@ -1,10 +1,10 @@
 set( MIRALL_VERSION_MAJOR 1 )
-set( MIRALL_VERSION_MINOR 6 )
-set( MIRALL_VERSION_PATCH 1 )
+set( MIRALL_VERSION_MINOR 7 )
+set( MIRALL_VERSION_PATCH 0 )
 set( MIRALL_SOVERSION 0 )
 
 if ( NOT DEFINED MIRALL_VERSION_SUFFIX )
-    set( MIRALL_VERSION_SUFFIX "pre") #e.g. beta1, beta2, rc1
+    set( MIRALL_VERSION_SUFFIX "prealpha") #e.g. beta1, beta2, rc1
 endif( NOT DEFINED MIRALL_VERSION_SUFFIX )
 
 if( NOT DEFINED MIRALL_VERSION_BUILD )