update for 1.2

Release_Notes.md

+6/15/2018: PALISADE v1.2 is released
+
+PALISADE v1.2 provides several important advancements and improvements to the library.  Most notably, we provide:
+
+* The Bajard-Eynard-Hasan-Zucca RNS variant of the BFV scheme is added to the library
+* The implementation of the Halevi-Polyakov-Shoup RNS variant of the BFV scheme is significantly improved
+* Large multiplicative depths (up to 100 and higher) for both RNS variants are now supported.
+* Several low-level optimizations, e.g., in Number Theoretic Transform and NTL multiprecision math backend, are implemented.
+* Multiple improvements in plaintext encodings.
+* Software engineering improvements: extended batteries of unit tests, cleaner design of the matrix class, better CryptoContext wrapper, etc.
+* Fixes for bugs which have been brought to our attention.
+
 1/29/2018: PALISADE v1.1.1 is released
 
 PALISADE v1.1.1 includes bug fixes and minor optimizations: