Updating build instructions in regard to protobuf.

INSTALL

@@ -14,10 +14,14 @@ A typical unix installation won't require any more steps than running:
   $ make
   # make install
 
-You don't need anything else than GNU Make and gcc. Under a Debian or
-Ubuntu system, this should boil down to the following package:
+You don't need anything else than GNU Make, gcc and autotools. Under a Debian
+or Ubuntu system, this should boil down to the following packages:
 
-  # apt-get install build-essential python-all-dev python-virtualenv
+  # apt-get install build-essential autoconf libtool
+
+Building the python wrapper requires the following:
+
+  # apt-get install python-all-dev python-virtualenv
 
 
 *******************************
@@ -68,33 +72,23 @@ Compiling and running grpc plain-C tests dont't require any more dependency.
 
 
 Compiling and running grpc C++ tests depend on protobuf 3.0.0, gtest and
-gflags. Although gflags and protobuf are provided in third_party, you will
-need to manually install these dependencies on your system to run these tests.
+gflags. Although gflags is provided in third_party, you will need to manually
+install that dependency on your system to run these tests.
 
 Under a Debian or Ubuntu system, you can install the gtests and gflags packages
 using apt-get:
 
   # apt-get install libgflags-dev libgtest-dev
 
-However, protobuf 3.0.0 isn't in a debian package yet: you'll need to compile
-and install it from the sources in the third_party. Note that if you already
-have the protobuf and protoc packages installed on your system, they will most
-likely interfere, and you'll need to uninstall them first.
+However, protobuf 3.0.0 isn't in a debian package yet, but the Makefile will
+automatically try and compile the one present in third_party if you cloned the
+repository recursively, and that it detects your system is lacking it.
 
 Compiling and installing protobuf 3.0.0 requires a few more dependencies in
-itself, notably the autoconf suite, curl, and unzip. If you have apt-get, you
-can install these dependencies this way:
-
-  # apt-get install unzip curl autoconf libtool
+itself, notably the autoconf suite. If you have apt-get, you can install
+these dependencies this way:
 
-Then, you can build and install protobuf 3.0.0:
-
-  $ cd third_party/protobuf
-  $ ./autogen.sh
-  $ ./configure
-  $ make
-  # make install
-  # ldconfig
+  # apt-get install autoconf libtool
 
 
 A word on OpenSSL