Merge pull request #525 from skeuomorf/installation-docs

Added canonical installation document with details about various platforms
diff --git a/AUTHORS.rst b/AUTHORS.rst
index ad27cec..0e3979a 100644
--- a/AUTHORS.rst
+++ b/AUTHORS.rst
@@ -12,3 +12,5 @@
 * Jarret Raim <jarito@gmail.com>
 * Alex Stapleton <alexs@prol.etari.at> (A1C7 E50B 66DE 39ED C847 9665 8E3C 20D1 9BD9 5C4C)
 * David Reid <dreid@dreid.org> (0F83 CC87 B32F 482B C726  B58A 9FBF D8F4 DA89 6D74)
+* Konstantinos Koukopoulos <koukopoulos@gmail.com> (D6BD 52B6 8C99 A91C E2C8  934D 3300 566B 3A46 726E)
+* Stephen Holsapple <sholsapp@gmail.com>
diff --git a/cryptography/hazmat/bindings/openssl/x509.py b/cryptography/hazmat/bindings/openssl/x509.py
index 840254a..e4021a1 100644
--- a/cryptography/hazmat/bindings/openssl/x509.py
+++ b/cryptography/hazmat/bindings/openssl/x509.py
@@ -119,6 +119,7 @@
 int X509_REQ_verify(X509_REQ *, EVP_PKEY *);
 EVP_PKEY *X509_REQ_get_pubkey(X509_REQ *);
 int X509_REQ_add_extensions(X509_REQ *, X509_EXTENSIONS *);
+X509_EXTENSIONS *X509_REQ_get_extensions(X509_REQ *);
 int X509_REQ_print_ex(BIO *, X509_REQ *, unsigned long, unsigned long);
 
 int X509V3_EXT_print(BIO *, X509_EXTENSION *, unsigned long, int);
@@ -165,6 +166,7 @@
 X509_STORE *X509_STORE_new(void);
 void X509_STORE_free(X509_STORE *);
 int X509_STORE_add_cert(X509_STORE *, X509 *);
+int X509_verify_cert(X509_STORE_CTX *);
 """
 
 MACROS = """
diff --git a/docs/hazmat/primitives/interfaces.rst b/docs/hazmat/primitives/interfaces.rst
index 2adad91..09a5a4c 100644
--- a/docs/hazmat/primitives/interfaces.rst
+++ b/docs/hazmat/primitives/interfaces.rst
@@ -204,6 +204,31 @@
         The public exponent. Alias for :attr:`public_exponent`.
 
 
+Hash Algorithms
+~~~~~~~~~~~~~~~
+
+.. class:: HashAlgorithm
+
+    .. attribute:: name
+
+        :type: str
+
+        The standard name for the hash algorithm, for example: ``"sha256"`` or
+        ``"whirlpool"``.
+
+    .. attribute:: digest_size
+
+        :type: int
+
+        The size of the resulting digest in bytes.
+
+    .. attribute:: block_size
+
+        :type: int
+
+        The internal block size of the hash algorithm in bytes.
+
+
 Key Derivation Functions
 ~~~~~~~~~~~~~~~~~~~~~~~~