Add git and mercurial as dependencies

DEVELOPERS.md

@@ -1,6 +1,16 @@
 ### Build Dependencies
 This installation document assumes Ubuntu 12.04 or later on x86-64.
 
+##### Install Git and GCC
+```sh
+$ sudo apt-get install git build-essential
+```
+
+##### Install Mercurial
+```sh
+$ sudo apt-get install mercurial
+```
+
 ##### Install YASM
 ```sh
 $ sudo apt-get install yasm

Makefile

@@ -3,7 +3,10 @@ MAKE_OPTIONS := -s
 
 all: getdeps cover install
 
-getdeps:
+checkdeps:
+	@./checkdeps.sh
+
+getdeps: checkdeps
 	@go get github.com/tools/godep && echo "Installing godep"
 	@go get code.google.com/p/go.tools/cmd/cover && echo "Installing cover"
 

checkdeps.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+echo -n "Checking dependencies for Minio.. "
+
+## Check all dependencies are present
+MISSING=""
+
+env git --version > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+  MISSING="${MISSING} git"
+fi
+
+env hg --version > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+    MISSING="${MISSING} mercurial"
+fi
+
+env gcc --version > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+    MISSING="${MISSING} build-essential"
+fi
+
+## If dependencies are missing, warn the user and abort
+if [ "x${MISSING}" != "x" ]; then
+  echo "ERROR"
+  echo
+  echo "The following build tools are missing:"
+  echo
+  echo "** ${MISSING} **"
+  echo
+  echo "Please install them "
+  echo "$ sudo apt-get install ${MISSING}"
+  echo
+  exit 1
+fi
+echo "SUCCESS"