[MRG] bug_fix

[haifeng-jin]

This pull request resolves #349 .

The pull request is ready to be merged.

The details of the pull request:
Initialize the weights on the skip connections.

[coveralls]

Pull Request Test Coverage Report for Build 1060

• 20 of 22 (90.91%) changed or added relevant lines in 5 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.05%) to 94.575%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
autokeras/net_transformer.py	9	10	90.0%
autokeras/nn/graph.py	2	3	66.67%

Files with Coverage Reduction	New Missed Lines	%
autokeras/nn/layers.py	1	94.65%

Totals
Change from base Build 1055:	-0.05%
Covered Lines:	2458
Relevant Lines:	2599

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💛 - Coveralls