Add support for manually disabling tcmalloc

For unknown reasons tcmalloc seems to not work properly on some
mac setups. The workaround until today is to manually edit [1]
CMakeLists.txt so that GraphLab is built without linking against
tcmalloc.

This patch introduces the `--no_tcmalloc` option to the configure
script (along with the CMake option -DNO_TCMALLOC) so that such
manual edits aren't really necessary when the user decides to
build GraphLab without tcmalloc.

Fixes #55. While I agree that the best approach would be to
actually fix the underlying problem, this patch enables mac
users facing the problem to work around the current issue more
easily.

NOTE: This is better viewed with the `-w` option to ignore the
indentation change incurred by adding the if()-endif() block.

[1]: https://groups.google.com/d/msg/graphlab-kdd/SGfjqej1TqM/XTRMWg7946cJ
Merge pull request #100 from caio/no_tcmalloc

Add support for manually disabling tcmalloc. Thanks Caio for your great contribution!!
typo in sssp from graph_analytics
Merge pull request #106 from luyi0619/master

typo in sssp from graph_analytics. The older version worked as well but this fix makes it cleaner. Thanks Yi!
first working version of adpredictor
Merge pull request #109 from dbickson/master

first working version of adpredictor
Update svdpp.cpp
Merge pull request #110 from jianpingjwang/master

Update svdpp.cpp
Enable use of implicit data in WALS
Merge pull request #111 from okurisama/master

Enable use of implicit data in WALS
forget to check in adpredictor makefile
Merge pull request #112 from dbickson/master

forget to check in adpredictor makefile
fixed bug in jacobi
Merge pull request #113 from dbickson/master

fixed bug in jacobi
fixed documentation based on error report by senthil
Merge pull request #116 from dbickson/master

fixed SVD documentation based on error report by senthil
change the parameters for svd
Ensure the correctness of id and row/col
Ensure the file name consistency

Ensure the file name consistent with the eigen_vector_normalization
Merge pull request #117 from parkerzf/master

Pull Request for the partitioning API